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Full text of "Radio Electronics (September 1982)"

Radio 



BUILD THE PICTURE PHONE 

ADAPTER AND SEND VIDEO 

OVER YOUR TELEPHONE 



$1.25 SEPT. 1982 




THE MAGAZINE FOR NEW IDEAS IN ELECTRONICS 






tie ins and outs of 

IDYING MAILORDER PARTS 

low to 

HAS TRANSISTORS CORRECTLY 

when designing analog circuits 

STEREO IMAGE EXPANDER 
or concert hall effects 

Iroubleshoot and repair 

MINI-CASSETTE RECORDERS 

;t«i-ny-step 




-A- 

MATic 



vouj^j 



"7U P48783" 



If we only tell you the features 
youll never guess the price. 

Leader has 6 great oscilloscopes from 15 to 35 MHz, 
with more features and the lowest list prices ever. 



I?b1ill 




We've designed brand new 
low and medium bandwidth 
oscilloscopes and built in 
many features you may never 
have seen in simitar units. 
Then we priced them well 
below the units they replace. 
Surprising? Not any more. It's 
exactly the kind of innovative 
technology and superb quality 
you've come to expect from 
Leader. 



trigee 

MHz 



;er holdoff 



Ever see 
on a 20 MHz scope.' 
Or 500 u-V sensitivity? 

Now Leader gives you these 
and so much more. Check it out: 

LBO-524 LBO-524L: 
35 MHz 

• CALIBRATED DUAL 
TIME BASE 

500 (ulV SENSITIVITY 

- 7 kV PDA 6" 
RECTANGULAR CRT 
INTERNAL GRATICULE 

• DELAYED SWEEP 
TRIGGERED FUNCTION 

- VARIABLE SWEEP 
HOLDOFF 

• ALTERNATE CHANNEL 
TRIGGERING 

. AUTO FOCUS 

• CHANNEL 1 OUTPUT 

LBO-523: 35 MHz 

• 7 kV PDA 6" 
RECTANGULAR CRT 
INTERNAL GRATICULE 
500 m-V SENSITIVITY 

• VARIABLE SWEEP 
HOLDOFF 

• ALTERNATE CHANNEL 
TRIGGERING 

• AUTO FOCUS 

• CHANNEL 1 OUTPUT 

CIRCLE « FOR PRODUCT DEMONSTRATION 
CIRCLE 5 FOR PRODUCT INFORMATION 





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t*t»r»rm 








500 u,V SENSITIVITY 
6'' RECTANGULAR CRT 
■ INTERNAL GRATICULE 

• ALTERNATE CHANNEL 
TRIGGERING 

• VARIABLE SWEEP 
HOLDOFF 

• AUTO FOCUS 
. CHANNEL 1 OUTPUT 

LBO-514A/LBO-513A: 
15 MHz 

• 1 mV SENSITIVITY 

• 0.5 jxS SWEEP SPEED 

• X-Y MODE CAPABILITY 

• LBO-514A AVAILABLE 
WITH 6 kV 
ACCELERATING 
POTENTIAL 



Our two-year warranty 
{even on the CRT) is backed 
by factory service depots on 
both coasts. Evaluation units 
are available to qualified 
customers. 

Call toll-free 
(800) 645-5104 

Contact us today for an 
evaluation unit, catalog 
showing over 60 Leader test 
instruments, the name of your 
nearest "Select" distributor 
and more information. 

For professionals 



who 
know 
the 



^JiT 



Instruments Corporation 



difference. 



380 Oser Avenue 

Hauppauge, N.Y, 11788 (516) 231-6900 

Regional Offices: 

Chicago, Los Angeles, Dallas 



Introducing incredible tuning accuracy at an incredibly 
affordable price: The Command Series RF-3100 
31 -band AM/FM/SW receiver" No 
other shortwave receiver brings in 
PLL quartz synthesized tuning and 
all-band digital readout for as low a 
price, • The tuner tracks and "locks" 
onto your signal, and the 5-digit dis- 
play shows exactly what frequency 
you're on. 

There are other ways the RF-3100 
commands the airways: It can travel 
the full length of the shortwave band 
(that's 1 .6 to 30 MHz). It eliminates interference when 
stations overlap by narrowing the broadcast band. 
It improves reception in strong signal areas with RF 
Gain Control. And the RF-3100 catches Morse 




RF-6300 8-band AM FM SW 



communications accurately with BFO Pitch Control. 
Want to bring in your favorite programs without lifting 
a finger? Then consider the Panasonic 
RF-6300 8-band AM/FM/SW receiver 
(1 .6 to 30 MHz) has microcomputerized 
preset pushbutton tuning, for program- 
ming 12 different broadcasts, or the 
same broadcast 12 days in a raw. Auto- 
matically. It even has a quartz alarm 
clock that turns the radio on and off to 
play your favorite broadcasts. 

The Command Series RF-3100 and 
RF-6300. Two more ways to roam the 

globe at the speed of sound. Only from Panasonic. 

Shortwave reception will vary with antenna, weather conditions, operators 
geographic location and other factors An outside antenna may be required lor 
maximum shortwave reception 

'< Based on a comparison ol suggested retail prices 



This Panasonic Command Series 

shortwave receiver brings the state of the art 

closer to the state of your pocket book . 



Mt HWtW 3MUUVO WUlYUStW MVWJC *uf* AMI TtMOtTOft 




\ «•' / 






vouiMf wt4-nwu wriwiv a*m wo puck 



Panasonic 



With PLL Quartz Synthesized Tuning and Digital Frequency Readout. 



Panasonic 

just slightly ahead of our time. 



CIRCLE 7 ON FREE INFORMATION CARD 



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Why use their flexible discs: 

BASF, Control Data, Dysan, IBM, Kybe, Maxell, 
Nashua, Scotch, Syncom, Verbatim or Wabash 

when you could be using 

MEMOREX 

high quality error free discs? 



8" 

8" 
8" 
8' J 



Product Description 

8" SSSD IBM Compatible (128 B/S, 26 Sectors) 
8" SSSD Shugart Compatible, 32 Hard Sector 
8" SSSD CPT 8000 Compatible, Soft Sector 
8" SSDD IBM Compatible (128 B/S, 26 Sectors) 
DSDD Soft Sector (Unformatted) 
DSDD Soft Sector (128 B/S, 26 Sectors) 
DSDD Soft Sector (256 B/S, 26 Sectors) 
DSDD Soft Sector (51 2 B/S, 15 Sectors) 
8" DSDD Soft Sector (1024 B/S, 8 Sectors) 
5W SSDD Soft Sector w/Hub Ring 
5V4" SSDD 10 Hard Sector w/Hub Ring 
5 1 /4" SSDD 16 Hard Sector w/Hub Ring 
5 1 A" DSDD Soft Sector w/Hub Ring 
5 1 /4" DSDD 10 Hard Sector w/Hub Ring 
SW' DSDD 16 Hard Sector w/Hub Ring 
5W' SSDD Soft Sector w/Hub Ring (96 TP1) 
5W DSDD Soft Sector w/Hub Ring (96 TPI) 

SSSD = Single Sided Single Density; SSDD - Single Sided Double Density 
DSDD = Double Sided Double Density, TPI = Tracks per inch 

Memorex Flexible Discs.. .The Ultimate in Memory Excellence 



Free Memorex Mini-Disc Offer- Save 10% 
Every carlo n of 1 M em ore* 5 V* i nch m i rti-d i sea sold by 
Communications Electronics, now has a coupon good 
for a tree Memorex mini-disc. For every case of 100 
Memorex mini-discs you buy from CE, you'll get 1 free 
mini-discs directly from Memorex, There is no limit to 
the number of discs you can purchase on this special 
offer. This offer is good only in the U.S.A. and ends on 
December 31, 1982. 

Quality 

Memorex means quality products that you can depend 
on. Quality control at Memorex means starting with the 
best materials available and continual surveillance 
Ihroughout the entire manufacturing process. The ben- 
efit of Memorex's years of experience in magnetic 
m ed I a p roduct i on, resu it i ng, for instance, i n proprietary 
coating formulations. The most sophisticated testing 
procedures you'll find anywhere in the business, 

1O0 Percent Error Free 

Each and every Memorex Flexible Disc is cert if ied to be 
100 percent error free. Bach track of each flexible disc 
Is tested, individually, to Memorex's stringent standards 
of excellence. They test signal amplitude, resolution, 
low-pass modulation, overwrite, missing pulse error 
and ext ra pu tse e rror. R igid q u atity audits are b u lit in to 
every step of the manufacturing process and stringent 
testing result In a standard of excellence that assures 
you, our customer, of a quality product designed for 
increased reliability and consistent top performance. 
Customer-Oriented Packaging 
T h e desk-top box co n tai n i ng ten d iscs is con ven I e n t f or 
filing and storage. Goth box labels and jacket labels 
provide full information on compatibility, density, sec- 
toring, and record length. Envelopes with multi-lan- 
guage care and handling instructions and and color- 
coded removable labels are included. A write-protect 
feature Is available to provide data security. 
Full One Year Warranty — Your Assure nee of Quality 
Memorex Flexible Discswill be replaced free of charge 
by Memorex if they are found to be defective in materials 
or workman sh i p within one year of t h e date of pure h ase. 
Other than replacement, Memorex will not be respon- 
sible for any da mages or losses (including consequential 
damages) caused by the use of Memorex Flexible 
Discs. 



Part* 


CE quant. 
1 00 price 
per disc (S 


3062 


2.09 


3015 


2.09 


3045 


2.99 


3090 


2.74 


3102 


3.34 


3115 


3.34 


3103 


3.34 


3114 


3.34 


3104 


3.34 


3481 


2.34 


3483 


2.34 


3485 


2.34 


3491 


3.09 


3493 


3.09 


3495 


3.09 


3504 


2.99 


3501 


3.99 



Quantity Discounts Available 

Memorex Flexible Discs ere packed 10 discs to a carton 
and 1 cartons to a case. Please ord« r c n ly i n i ncrementa 
of 1 00 u n I ts f or q u a nt ity 1 00 pricing. We are also willing to 
accommodate your smaller orders. Quantities less than 
1O0 units are available in increments of 10 units at a 10% 
surcharge. Quantity discounts are also available. Order 
500 or more discs at the same time and deduct 1%; 1,000 
or more saves you 2%; 2 r 00O or more saves you 3%; 5,000 
or more saves you 4%; 10 r 000 or more saves you 5%; 
25,000 or more saves you 6%; 50,000 or more saves you 
7% and 1 00,000 or more discs earns you an 3% discount 
off our super low quantity 100 price. Almost ail Memorex 
Flexible Discs are immediately available from CE. Our 
warehouse facilities are equipped to help us get you the 
quality product you need, when you need it. If you need 
further assistance to find the flexible disc that's right for 
yorj r call the Memorex compatibility hotline. Dial toll-free 
800-538-60BQ and ask for the flex/We oVsertoftffle extension 
0997. In California dial 800-6 7 2- 35 £5 extension 0997. 
Outside the USA dial 408-987-O997. 
Buy with Confidence 

To get the fastest delivery from CE of your Memorex 
Flexible Dlscs h send or phone your order directly lo our 
Computer Products Division. Be sure to calculate your 
price using the CE prices in this ad. Michigan residents 
please add 4% sales tax. Written purchase orders are 
accepted from approved government agencies and most 
well rated llrms al a 30% surcharge lor net 30 billing. All 
sales are su bject to avai lability, acceptance and verif Icatl on. 
All sales are final. Prices, terms and specifications are 
subject tochange withoul notice. Out of stock items will be 
placed on backorder automatically unless CE is Instructed 
differently. Minimum prepaid order £50.00. Minimum 
purchase order S200.00. International orders are invited 
with a $20.00 surcharge for special handling in addition to 
shipping charges. All shipments are F.O.B. Ann Arbor. 
Michigan. No COD's please. Non-certified and foreign 
checks require bank clearance. 

Mail orders tor Cornmuntcitlont Electronics, Bo* 1002, 
Ann Arbor. Michigan 4S106 U.S.A. Add S3.00 par case or 
partial-case of 100 8-inch discs or $6.00 per case or partial 
case of 1 00 svt-mch mini-discs for U-P.S- ground shipping and 
handling in the continental U.S.A. If you have a MasterCard or 
Visa card, you may call anytime and place a credit card order. 
Order toll-tree In the U-S- Dial 300-521-4414. If you are 
outside : he U. S. or in M ich Igan, dial 3 1 3-994-4444. Order you r 
high duality, error tree Memorex discs today. 

Copj'igw ' sob? GwiKnunKnOent EHel'omei" Ad •CSiTSZ 

CIRCLE 16 ON FREE INFORMATION CARD 



Free disc offer 
Save 10% 






MtnlwCocd'. 



Order Toll-Free! 
(800)521-4414 

In Michigan (313) 994-4444 




For Data Reliability — Memorex Flexible Discs 



a 



COMMUNICATIONS 
ELECTRONICS™ 
Computer Products Division 

854 Phoenix □ Box 1 002 □ Ann Arbor. Michigan 4S1 06 U.S.A. 

Cl II TOLL-FREE (BOO) 53 1 -441 4 or out. Wo U. S. A, (313) 991-4444 




Electronics 

Electronics publishers since 1908 



THE MAGAZINE FOR NEW 
IDEAS IN ELECTRONICS 



September 1982 Vol. 53 No. 9 



SPECIAL FEATURE 53 



BUYING MAIL-ORDER COMPONENTS 

Mail-order is sometimes the only way to obtain the components 
you need. Here are some tips you should know and pitfalls you 
should avoid. Karl T. Thurber, Jr., W8FX 



BUILD THIS 45 



49 



63 



HEART-RATE MONITOR 

Know the state of your health and fitness. This project displays 
your heart rate in beats-per-minute by simply attaching an opto- 
electronic sensor to your finger. Robert Grossblatt 

PICTURE PHONE 

Part 2 — Adapter sends video pictures over the telephone line to 
a remote location. Josef Bernard 

STEREO IMAGE EXPANDER 

Part 2— Hi-fi adapter adds an extra dimension to your recorded 

music. Joel Cohen 



TECHNOLOGY 



CIRCUITS AND 

COMPONENTS 



4 VIDEO ELECTRONICS 

Tomorrow's news and technology in this quickly changing industry. 
David Lachenbruch 

40 SATELLITE TV NEWS 

The latest happenings in communications technology, 
Gary H. Arlen 

71 ALL ABOUT PULSE GENERATORS 

How to use a pulse generator to test an analog circuit. 
Charles Gilmore 

84 STATE-OF-SOLID-STATE 

DC voltage-controlled switches. Robert F. Scott 

42 NEW IDEA 

Electronic thermometer. 

59 HOW TO DESIGN ANALOG CIRCUITS 

Proper transistor operation requires proper biasing. Learn about 
biasing circuits and how to design them, Mannle Horowitz 

74 HOBBY CORNER 

Learning about microprocessors. Earl "Doc" Savage, K4SDS 



VIDEO 92 SERVICE CLINIC 

Color-burst reference oscillators. Jack Darr 

92 SERVICE QUESTIONS 

Radio-Electronics' Service Editor solves technicians' problems. 



AUDIO 


66 


REPAIRING PORTABLE CASSETTE RECORDERS 

How to troubleshoot and repair these popular recorders. 
Homer L. Davidson 


RADIO 


78 


COMMUNICATIONS CORNER 

Touch-Tone devices and FM Adjustments. Herb Friedman 


COMPUTERS 


BO 


COMPUTER CORNER 

Electronic worksheets. Las Spindle 


EQUIPMENT 
REPORTS 


26 
32 


Sencore Model SC61 Waveform Analyzer. 
McKay/Dymek General Coverage Receiving System 



DEPARTMENTS 



12 


Advertising and Sales Offices 


22 


Letters 


138 


Advertising Index 


114 


Market Center 


111 


Books 


106 


New Literature 


14 


Editorial 


95 


New Products 


139 


Free information Card 


6 


What's News 



ON THE COVER 

Using an otpo-electronic sensor that 
attaches to your finger, this battery- 
powered monitor displays your 
heart rate in beats-per-minute on a 
digital display. Knowing how your 
heart rate varies under different cir- 
cumstances can give you an idea of 
your physical condition. Get started 
building yours today. The story 
starts on page 45, 




HOW TO PROPERLY BIAS a transistor circuit Is 
the subject of this month's analog design 
series. Must reading If your designs are to func- 
tion the first time you plug them in. The story 
starts on page 59. 




HOW TO TROUBLESHOOT AND REPAIR port- 
able cassette recorders. The best results are 
obtained with a logical troubleshooting 
approach. The story starts on page 66. 



Rad Id- Electronics, (ISSN 0033-7862) Published monlhly 
by Gernsback Publications, Inc.. 200 Park Avenue South, 
New York, NY 10003. Second-Class Postage Paid at New 
York, N.Y. and additional mailing offices. One-year subscrip- 
tion rate: U.S.A. and U.S. possessions. $13.00, Canada, 
$16,00. Other countries, S20.50 (cash orders only, payable 
in U.S.A. currency,} Single copies $1.25. © 1982 by Gerns- 
back Publications, Inc. All righls reserved. Printed in U,S,A. 

Subscription Service: Mall all subscription orders, 
changes, correspondence and Posfmaster Notices of un- 
delivered copies (Form 3579) lo Radio-El ecironics Sub- 
scription Service, Box 2520. Boulder, CO 80322. 

A stamped self-addressed envelope must accompany ali 
submitted manuscripts and/or artwork or photographs if their 
felum is desired should they be rejected. We disclaim any 
responsibility tor the loss or damage of manuscripts and/or 
a rtwo rk o r p notoo ra phs wh iie in our possession or otherwise. 



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'As ,i service to readers, Radio-Electronics publishes available plans or Information relating to newsworthy products, techniques and scientific and technological developments. 
Because cf possible variances in the quality and condition of materials and workmanship used by readers, Radio- Electro nice disclaims any responsibility for the sate and proper 
functioning of reader-built projects baaed upon or from plans or Information published In this magazine. 



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VIDEO ELECTRONICS 



DAVID LACHENBRUCH 
CONTRIBUTING EDITOR 




DISC DATA 



The often-postponed market launch of the Japanese VHD videodisc system is now sched- 
uled for summer 1983. Pioneer (see photo) has expanded its line of LaserVision players to 
three — the original model at about $750, a new remote-control unit at $800, and a version 
without remote and random frame access at $600. RCA added a fourth CED player to its line 
described here last month — a model with wireless remote control and all-eiectronic on-set 
controls at $449.95. 



DIGITAL TV 



"Computer TV" could become a byword — or an advertising point — next year when the first 
sets with completely digital signal-processing circuits are scheduled to be introduced. The 
circuits are contained on five VSLI IC's developed by ITT Semiconductor and being offered 
worldwide to TV set makers. ITT claims the IC's replace an average of 20 IC's, 500 to 600 
transistors and other components, and make possible production of a better TV set for the 
same or less money. Among the claimed advantages: The set can be self-testing and 
self-adjusting, automatically compensating for picture-tube aging. The same set can be 
"programmed" to accommodate NTSC or PAL color. Stereo audio, when available, comes 
"free" (except for the speakers), merely by programming. The design will accommodate 
digital sound input, or digital input from a computer. It makes possible the later addition of 
low-cost "peripherals," such as digital ghost elimination, high-definition by means of line 
interpolation, and elimination of flicker by interpolation of additional fields or frames. The first 
production prototype digital TV will be shown by ITT's Standard Elektrik Lorenz of Germany. 
Among at least eight set makers working with the ITT circuits is Zenith, which could be the first 
to introduce a digital set here. 



BETA HI-FI 



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How can you get true high-fidelity stereo from a half-inch home video recorder? The VHS 
manufacturers are adding a second audio track and Dolby noise reduction, but that provides a 
50-10,000 Hz frequency response, at most. Headed by Sony, the Beta group has been 
showing a proposed new "Beta Hi-Fi" system that can provide better audio specs than an 
open-reel tape recorder, but is still compatible with existing Beta recorders and tapes. 

Beta's magic trick is to leave the current longitudinal audio track alone and put a new stereo 
sound track on an FM carrier in the helical video track. The result is "nearly digital" sound, with 
an 80-dB range, far above the 30- to 40-dB range of current recorders, with a frequency 
response of 20-20,000 Hz at 0.3% distortion, and inaudible wow and flutter. Recorders built 
for the hi-fi system would also be able to play the longitudinal track on old tapes, and new 
prerecorded tapes would have a longitudinal mono track plus the helical hi-fi stereo pair, to 
preserve compatibility. An extra bonus is the ability to have three separate soundtracks on 
mono tapes — three different languages, for example. Sony claims that such a helical-audio 
feat can't be accomplished on VHS recorders because their head drums are too small, 
resulting in picture degradation. But the VHS camp has yet to be heard from on the subject. If 
they go ahead with the project, Beta manufacturers say they can have recorders in the hi-fi 
format on the market around mid-1983. r-e 



ow you can 
love up to 
hike." 



We've got great news for people 
who've been holding out for a high 
quality, high performance DMM at a 
moderate price; Fluke's new nine 
function model D 8(M is now available 
at select electronics supply stores. 

With a suggested I ; .S. price of only 
$249 and features vou won't find in am 1 
other handheld DMM, the D8M is an 
exceptional value. 1 lere's why. 

Ijogic level and continuity 
testing: A real time-saver for 
troubleshooting passive circuits in pcb's, 
rabies, relay panels and the like. Hie 
D804 has a switch-selectable audible 
tone and visual symlwls to indicate 
continuity or logic levels. 

Direct temperature readings in 
°C: Used with any K-type 



thermocouple, the I) 8(M delivers fully- 
compensated readings in °C from 
■m°C to + 1265°C. for checking 
heating and refrigeration systems. 

I*eak hold feature captures 
transients: A short-term memory in 
the DXH captures and holds the peak 
reading of a motor starting current. 

And more: (XI % ljasic dc accuracy, 
conductance, 26 measurement ranges, 
battery, safety-designed test leads and a 
one year parts and latxir warranty, A 
full line of accessories is also available 

,... i i *i__ * i_:i:,- .. 



of your I )MM. 

Ask your dealer about the 
powerful, versatile DHO-i and the rest of 
Flute's new Series D line of low-cost 
digital multimeters. 






i3\0itljr.--^\^'j¥"l 



leader in DMM s. 
Now weVe designed 
one for you. 



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Suggested U.S. list price 

ichnical data circle No. 15 

1330-0/D804 

RE 9/82 



If your dealer doesn't carry Series I > 
Multimeters yet, call this number. We'll be 
happy to tell you who does. l-8(X>-426-(M61 



FLUKE 



WHAT'S NEWS 



Sharp reducing copier 
talks back to user 

A new dry, any-paper desktop 
copier that talks to its user, makes 
reduced-size copies, can be auto- 
mated, and helps diagnose its own 
troubles, has been introduced by 
Sharp Electronics Corp., head- 
quartered in the United States at 
Paramus, NJ. 

The new model SF-781 speaks 
from a built-in voice synthesizer 
that emits electronic tones in a 
series that the ear hears as clear, 
easily understood sentences. 
When the user makes a reduced- 
size copy, the machine reminds 



him: "Check the paper size, "and if 
he leaves his material in the ma- 
chine and starts to walk away, it 
calls out: "Remove the original." If 
there is a paper misfeed, the SF- 
781 warns the user and tells where 
to look for the cause. 

The machine also warns if paper 
or toner needs replenishing, and if 
the machine is out of order. The 
copter's total vocabulariy is nine 
sentences, all selected to boost 
efficiency and save time. 

An advanced self-diagnostic 
system, aided by a microcompu- 
ter, pinpoints many problems by 
voice or LED alphanumeric dis- 
play—quick but thorough diagnos- 



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SECRETARY IS USING THE SF-781 with SF-461 automatic document feeder 
(right) and SF-410 sorter (in front of the secretary). Those can be added to the 
copier to permit the equipment to grow as the user's needs may require. 



tic tests can be run from the front 
panel by pressing buttons. 

The copier will take originals up 
to 1 1 x 17 inches. From that size, 
copies can be reduced to 8Vfe x 1 4 
or 8V2 x 1 1 inches. Line artwork 
can often be reduced so cleanly 
that it can be used for reproduc- 
tion. Two 8V2 x 11 -inch pieces 
can be placed side-by-side for 
reproduction. The SF-781 picks up 
a broad range of colors, including 
the difficult blue tones. 



Transistors move into 
high-voltage range 

Motorola, in what it refers to as 
"a major expansion of MOS power 
transistor technology," has in- 
troduced eight new devices in the 
"sparsely populated 550- volt and 
up" field. The new devices are in- 
tended for power supplies operat- 
ing from 230 and 460-volt lines. 
They are supplied in four voltages, 
with breakdown rating from 550 to 
900 volts, and up to 3 amperes of 
continuous drain current. 

The new devices are intended 
for such equipment as transmitt- 
ers, radar, and medical electronics 
using high-power, high-voltage, 
tube-operated circuitry. Prices are 
in the $7 to $1 range. Data sheets 
are available from Motorola at P.O. 
Box 20912, Phoenix, AZ 85036. 



Children, aged 3 to 13, 
are new computer market 

The Learning Co. of Porto la Val- 
ley, CA, is henceforth devoting its 
efforts to developing and selling in- 
teractive computer software for 
children whose ages range from 3 
to 1 3 years. The programs are for 
use in the home, and include play 
with learning, encouraging 
participation by both children and 
their parents. 

The first two programs offered 
are Moptown and Magic Spells. 
They are available from Apple 
Computer distributors under Ap- 
ple's Special Delivery Software 
programs. Moptown is a set of 1 1 
logic games; Magic Spells is a 
word game that combines large 
text, color graphics, and music. 

The games are designed for par- 
ents who wish to encourage their 



children to learn in an entertaining 
and unthreatening way, The pro- 
gram guides the child through a 
series of adventures that promote 
original thinking. There is no vio- 
lence and no wrong answers to 
discourage the child, 

Founded in 1980 as Advanced 
Learning Technology by Dr. Ann 
Piestrup, the company pioneered 
the development of children's pro- 
grams with interactive software 
featuring color graphics and an- 
imation, working under grants from 
the National Science Foundation 
and the Apple Education Founda- 
tion. Its change of name marks its 
move from a grant-funded organ- 
ization to a commercial firm. 



New plant will meet 
videodisc demands 

RCA has commenced construc- 
tion in Indianapolis of a new $19 
million facility for manufacturing 
the compound essential in making 
"CED" videodiscs. That will be 
used to support the expanding disc 
manufacture at the company's 
Rockville Road plant in In- 
dianapolis, as well as to supply 
other manufacturers worldwide. 

The compounding facility blends 
the plastic, carbon, and other 
materials that are used in pressing 
the conductive RCA discs. The 
blended material is in the form of 
pellets, which are formed into a 
mass and then placed between the 
two stampers of an automatic com- 
pression molding press to make 
the final disc. The new plant will be 
able to process 50,000 pounds of 
raw material daily. 

In addition to the new 55,000- 
squ are -foot compounding facility, 
RCA has completed a new power 
plant that will be able to produce 
the energy that will be needed for 
60 disc presses. 



Satellite-to-home 
broadcasts In sight 

The Satellite Television Corp 
(STC) a subsidiary of COMSAT, 
has received four bids to construct 
direct-broadcast satellites (DBS) 
for STC's satellite-to-home pay-TV 
service. The companies bidding 
were Ford Aerospace and Com- 
munications Corp, General Elec- 
continued on page 12 



TCIZ OOnO MULTI-PURPOSE 
lZr\ C-£\)\J OSCILLOSCOPES 



THE PERFORMANCE/ 
PRICE STANDARD 



Now! A 60 MHz Tektronix scope 
built for your bench. 




In 30 years of Tektronix oscil- 
loscope leadership, no other 
scopes have recorded the 
Immediate popular appeal of 
the Tek 2200 Series, the Tek 2213 
and 2215 are unapproached for the 
performance and reliability they 
offer at a surprisingly affordable 
price. 

There's no compromise with 
Tektronix quality: The low cost is the 
result of a new design concept that 
cut mechanical parts by 65%. Cut 
cabling by 90%. Virtually eliminated 
board electrical connectors. And 
obviated the usual cooling fan. 



Yet performance is written all over 
the front panels. There's the band- 
width for digital and analog circuits. 
The sensitivity for low signal mea- 
surements. The sweep speeds for 
fast logic families. And delayed 
sweep for fast, accurate timing 
measurements. 

The cost: $1100 for the 2213*. 
$1400 for the dual time base 2215. 

You can order, or obtain more 
information, through the Tektronix 
National Marketing Center, where 
technical personnel can answer 
your questions and expedite 
delivery, Your direct order includes 



probes, operating manuals, 15- 
day return policy and full Tektronix 
warranty. 

For a demonstration stop by your 
local Tektronix Sales Office. 



ORDER TOLL FREE 

1-800-426-2200 

Ask for Department J0133 

In the state of Washington, 
Call (206) 253-5353 collect. 



■Piice FOB Beavenon. OR 



Ttektronix 

COMwrrEOTO EXCELLENCE 



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Now! Learn on the latest, 

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25" Heath/Zenith 

color TV with state-of 

the-art features 

• 6-function infrared remote control 

• space phone lets you answer or call from your 
chair 

• microprocessor-controlled PLL varactor tuner 

• 82 VHF/UHF, 35 cable channels 

• 24-hour programmable channel selection 

• electronic time display 

• 4-speaker FM sound system 

• choice of three cabinets at student 
discount 




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We've taken the 
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ble and perform ex- 
periments on your 
Heathkit/Zenith. 
Only NRI combines 
such complete 
training with such 
up-to-date equipment 




Choice of 

Three 
Specialties 

And only NRI 
gives you the opportun- 
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of three areas. You get 
the same complete 
training covering TV, 
audio systems, and 
video recorders, but you 
select your own specialty 
for practical, hands-on 
training. 

You can choose 
to build the Heath/ 
Zenith color TV; special- 
ize in audio systems and 
build your own AM/ 
FM stereo system; or 
take your bench training 
with remote-controlled 
videocassette recorder 
featuring NRI training 
on videotape. No matter 



Choice of specialty training on TV, stereo, or VCR 

which specialty you elect, your prac- 
tical training also includes experi- 
ments and demonstrations with 
the exclusive NRI Discovery 
Lab® and your own profes- 
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equipment is yours to use 
and keep. 

Learn in Your 
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No need to quit 
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trains you in your own home at your 
convenience. You're a class of one 
with complete course materials, 
practical training on the latest 
equipment, and the backing of a mil 
staff of professional electronics 
educators. NRI brings it all to you. 



The Professional's 
Choice 

A million and a half stu- 
dents have already chosen the 
NRI way. And over half the prac- 
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Free Catalog... 
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Get all the facts on 
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11 



WHAT'S NEWS 



continued from page 16 



trie Co., Hughes Aircraft Co., and 
RCA Astro Electronics, 

STC's Request for Proposals 
(issued January 13) were for con- 
struction of two satellites (one op- 
erating and one spare) which STC 
would use for satellite-to-home 
pay-TV service over an area 
approximating the U.S. Eastern 
Time Zone. The satellites are 
scheduled to operate on the 12- 
and 17-GHz bands. 

The construction program is ex- 
pected to take more than three 
years, and the service would begin 
in late 1985 or early 1 986, STC will 
offer three channels of premium 
pay television, without advertising. 
Individual subscribers would re- 
ceive STC's pay-TV service on 
small, inexpensive home re- 
ceiving-antennas. 

Optical system tracks 
distant satellites 

The first of five Ground-based 
Electro-Optical Deep Space Sur- 
veillance Systems (GEODSS) has 
gone into action at the White 
Sands Missile Range in New Mex- 
ico, it will track optically satellites 
that orbit well above the range of 
most radars. GEODSS replaces 
an older camera system that re- 
quired developing photographic 
plates and examining them with a 
microscope, usually about an 



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hour's work. Sighting and 
identification with GEODSS is 
almost instantaneous. 

GEODSS's telescopes can pin- 
point the location of all satellites 
above 3,000 miles, especially 
those that orbit at 22,000 miles 
above the equator. The telescopes 
combine camera optics and com- 
puters and can see objects 1 0,000 
times dimmer than the human eye 
can detect. They are are able to 
spot an object the size of a soccer 
ball more than 22,000 miles away. 
In operation, they fix on the stars 
and pick up any objects moving in 
front of them. 

The telescope search is auto- 
matic, and the images it captures 
are recorded on a television 
camera. One hundred pictures a 
minute are converted into digital 
pulses and fed into a computer that 
filters out the (relatively) stationary 
surrounding stars and displays the 
satellites as streaks of light on 
video monitors. 

To protect its own satellites from 
possible destruction, the Air Force 
must know what is in space and 
whether it is friend or foe. That in- 
formation will be supplied by the 
GEODSS network. Sites in Korea 
and Hawaii are expected to be op- 
erational sometime this year, and 
an Eastern Atlantic and an Indian 
Ocean station will be in operation 
by the mid-1 980's. 




AIR FORCE TECHNICIANS TRACK SATELLITES at the ground-based Electro- 
Optl cal Deep S p a ce S u rve 1 1 la nee Sy ste m f aci t ity i n New M ex ico . It is t he f i rst o1 
five world-wide stations that will keep track of ati man-made satellites in orbit 
within a range of 22,000 miles. 



Anti-scanner ordinance 
tossed out in Philly 

Municipal Court Judge J. Earl 
Simons ruled that Section 10-817 
of the Code of Philadelphia Ordi- 
nances is unconstitutional. The 
ordinance, enacted in 1967, made 
access to police and fire radio 
channels illegal. It was not en- 
forced until late in 1981, when the 
city interpreted the law to apply to 
radio scanners and arrested 
several owners and employees of 
retail stores for selling scanners. 

The judge stated, among other 
things: "Individuals use scanner 
radios for personal entertainment 
or security purposes. Group use is 
endorsed — and in fact encour- 
aged — by local law enforcement 
agencies, which conduct pro- 
grams to teach the use of such 
scanner radios as a crime com- 
batant. ... There is no evidence to 
suport the contention that access 
to police or fire channels increases 
crime, or the risk thereof ... on the 
contrary, it demonstrates a 
markedly decreased risk of crimi- 
nality when such scanners are em- 
ployed by the citizenry. The con- 
clusion is compelled that the ordi- 
nance is unconstitutional." 

The judge then ruled that the 
citations be dismissed and the de- 
fendants discharged. 



New state voice network 
promises greater economy 

The State of Washington has 
contracted with the Action Com- 
munications System Div of Hon- 
eywell for a Roadrunner Network 
Management System, to replace a 
Common Channel Switching 
Arrangement (CCSA) leased from 
Pacific Northwest Bell. 

The state has spent nearly $12 
million annually for long-distance 
telephone services provided by the 
CCSA leased network system, ft is 
expected that the new systems 
can save about $5 million in annual 
long-distance costs. Average call- 
ing rates will be reduced from 12 
cents to 6.5 cents per minute by 
using the least-cost routing and 
management possibilities offered. 

A network of intermachine 
trunks and PBX tie lines will in- 
terconnect four switching centers 
at Olympia, Seattle, Spokane, and 
Vancouver with government PBX 



facilities across the state. The 
2,656 port statewide network will 
utilize 4,800-baud data links be- 
tween the four switching centers 
for "took ahead" routing and data- 
base maintenance and di- 
agnostics. 

G-E applies for a new 
consumer phone service 

The General Electric Co. has 
applied for a total of 9 MHz in the 
900-MHz band, for a new con- 
sumer-oriented mobile com- 
munications service. The alloca- 
tion would be divided into two 4.5- 
MHz bands separated by 45 MHz. 
That would provide 1 50 channels 
of 30 kHz each. 

The new Personal Radio Home 
Communications Service (PRCS) 
would be designed to augment the 
limited communications services 
already available to mobile con- 
sumers. It would provide the user 
with an affordable quality service 
for private communications within 
a user's normal driving area. 

The system will consist of a base 
station tied into the user's tele- 
phone, and mobile units installed 
by users in their vehicles. The typ- 
cial range with the system would 
be in the order of 5 miles, which 
can be increased to approximately 
15 miles by using strategically lo- 
cated repeater stations. There 
would be a nominal charge access of 
any of those. Repeaters would not be 
interconnected. 

An additional communications 
feature is automatic interconnec- 
tion to the public telephone net- 
work through the base station. 

New photovoltaic cell 
works with low light 

A high-performance photovolta- 
ic module that produces 40 watts 
of peak power with 35 solar cells 
has been developed by Arco Solar 
(a subsidiary of Atlantic Richfield) 
atChatsworth, CA. 

Using single- crystal silicon cells, 
the module can charge batteries at 
5 to 10 percent of noonday sun. 
The manufacturer claims that un- 
der such tow light conditions, the 
new cells can deliver up to 25 per- 
cent more energy than typical 
modules of polycrystailine design. 

The new module, M51, mea- 
sures 1 x 4 feet and is 1 0.75 per- 
cent efficient. R-E 



brkbench 



OK Machine & Tool Corporation 

3455 Conner St., Bronx.N.Y. 104V5 U.S.A. 
Tel.(212) 994-6600 Telex 125091 

CIRCLE 17 ON FREE INFORMATION CARD 



EDITORIAL 



"My Kingdom For A 



How many times have you decided to build a project only to find 
that the parts list contains components that are almost impossible to 
obtain locally? Or, how many times have you used your best 
troubleshooting skills to locate a bad component on a PC board only 
to find that the component might as well be a proprietary unit from a 
Titan missile. Unfortunately, we've all found ourselves faced with that 
situation at one time or another. 



Let's face it, in today's "high-technology" society, the electronic 
components that we very often need are becoming more and more 
difficult to obtain locally. Perhaps it is because the components that 
we are looking for are becoming more complex. Or, perhaps our local 
suppliers are finding it necessary to become more specialized. What- 
ever the reasons may be, understanding them won't help us when 
we're faced with the situation of trying to obtain a specific component. 



As bad as the situation might seem, especially to those of us that 
are not living in or near a large metropolitan area, we are not totally 
helpless. Fortunately, there are a large number of mail-order firms that 
supply electronics components. While I'll admit that ordering an 
electronic component from a mail-order supplier is not as convenient 
as walking into your local supplier, at least the mail-order supplier is 
more likely to have a larger and more diversified inventory. 



While the majority of the mail-order suppliers are quite reputable, 
not all of them are on the up and up. Screen the mail-order suppliers 
before you buy from them. First, if the ads appear month after month 
in Radio-Electronics magazine, you can be confident that they are 
reputable. Use the free information card at the back of the magazine 
to order catalogs from those suppliers and keep them handy. Catalogs 
are great for locating components that you need and they contain val- 
uable ordering information when you're actually ready to order a com- 
ponent. 



I can't possibly cover all the aspects of purchasing mail-order com- 
ponents in just one editorial page. The subject is important and we are 
presenting part 1 of a two-part series entitled "The Ins and Outs of 
Buying Mail-Order Components." Read the series and request as 
many catalogs as you can from the mail-order suppliers. They will be 
your best protection against being stuck for hard-to-find components in 
the future. 



z^^i 




ART KLEIMAN 
Editor 



Eleotronios 



Hugo Gernsback (1884-1967) founder 
M. Harvey Gernsback, editor-in-chief 
Larry Steckler, GET, publisher 
Arthur Kiel mart, editor 
Josef Bernard, K2HUF, technical editor 
Carl Laron, WB2SLR. assistant editor 
Jack Darr, GET, service editor 
Robert F. Scott, semiconductor editor 
Herb Friedman, communications editor 
Gary H. Aden, contributing editor 
David Lachenbruch. contributing editor 
Earl "Doc" Savage, K4SDS, hobby editor 
Ruby M. Yee, production manager 

Robert A. W. Lowndes, production 

associate 
Stefanie A. Mas, production assistant 
Joan Roman, circulation director 

Arline R. Fishman, 

advertising coordinator 



Radio-Electronics is indexed in Applied 
Science & Technology Index and Readers 
Guide to Periodical Literature. 



Gernsback Publications. Inc. 
200 Park Ave. S.. Mew York. NY 10003 
President: M, Harvey Gernsback 
Vice President: Larry Steckler 

ADVERTISING SALES 212-777-6400 

Larry Steckler 

Publisher 

EAST 

Stanley Levitan 
Radio -Electronics 
200 Park Ave. South 
New York, NY 10003 
212-777-6400 

MIDWEST/Texas/Arkansas/Okla. 

Ralph Bergen 

The Ralph Bergen Co.. Inc. 

540 Frontage Road— Suite 325 

Northfield. Illinois 60093 

312-446-1444 

PACIFIC COAST 
Mountain States 
Marvin Green 
Rad io-E lee Iron i cs 
41 3 So. LaBreaAve 
Los Angeles, Ca 90036 
213-938-0166-7 

SOUTHEAST 

Paul McGinnis 

Paul McGinnis Company 

60 East 42nd Street 

New York. NY 10017 

212-490-1021 



5£02£\, 




14 



Here's a professional, portable 
DC-20 MHz Oscilloscope with 
build it yourself Heathkit savings 



Heaihkii 













Compact enough to fit under an airplane 
seat, the Heathkit IO-3220 represents out- 
standing value in its class. Weighing only 
16 pounds, the IO-3220 is designed for field 
service troubleshooters who need a light, 
portable battery-operated scope for use 
where AC power is not available. 

Dual-trace versatility: The IO-3220 allows you to com- 
pare two different signals simultaneously- to make input/ 
output comparisons, check phase relationships and 
accomplish other complex measurements. Algebraic 
functions add versatility. 

Special invert display function: Enables you to com- 
pare two waveforms that are nearly 1 80 degrees out of 
phase- by inverting one of the waveforms. 



X-Y inputs for Lissajous measurements: 

Feed two separate input signals to the IO-3220. 

Wide DC-20 MHz bandwidth: The IO-3220 
can measure a very wide range of input signals. 

Outstanding sensitivity: Vertical signals as 
low as 2 millivolts can be accurately measured 
by the very sensitive IO-3220. Accuracy is as 

high as 3 percent (from 20-30 deg. C), on both vertical 

and horizontal measurements. 

Save more than 30% when you build it yourself; The 

IO-3220 Portable 20 MHz Oscilloscope Kit is value-priced 
at just $689.95." 

Easy to build: Thorough Heathkit assembly manuals 
take you step-by-step, from unpacking to final plug-in. 
Anyone can do it. And experienced service techs are just 
a phone call away, to help you during building or servicing. 



FREE CATALOG 

Complete details on Heathkit oscilloscopes 
- and nearly 400 other electronic kits for your 
home, work or pleasure- are in the new 
Heathkit catalog. Send the coupon at right 
for yours today, or pick one up at any of the 
65 convenient Heathkit Electronic Centers" * 
located throughout the U.S. and Canada. 
If coupon is missing, write Heath Co., Dept. 
020-934, Benton Harbor, Ml 49022. 




-Mail Order. FOB Ben ion Harbor. Ml. 
Also available assembled, mail order priced at 5995,00, FOB. Prices, speolications 
and product availability subject to change without notice, ' ■ See the while pages ol 
your telephone Book for the Heaihkii Electronic Center nearest you Heathkil Elec- 
tronic Centers in the U.S. are operated by Veritechnology Electronics Corporation 
" '-owned subsidiary of Zenith Radio Corporation 



and produ 
your telep 
Ironic Cor 
awhoity-c 



MAIL TO: Heath Company, Dept. 020-934 
Benton Harbor, Ml 49022 

D YES, Please send me your free Heathkit Catalog. 
I'm not currently receiving your catalog. 

N a me 



Address. 
City 



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Introducing the 
Sinclair ZX81. 

If you 're ever 
going to buy a personal 
computer, now is the time 
to do it. 

The Sinclair ZX81 
is the most powerful, yet 
easy-to-use computer 
ever offered for any- 
where near the price: 
only $99.95* completely assembled. 

Don't let the price fool you. The ZX81 has 
just about everything you could ask for in a per- 
sonal computer. 
A breakthrough in personal computers. 

The ZX81 is a major advance over the origi- 
nal Sinclair ZX80-the first personal computer to 
break the price barrier at $200. 

In fact, the ZX81 's 8K extended BASIC offers 
features found only on computers costing two or 
three times as much. 

Just look at what you get: 
■ Continuous display, including moving graphics 

Sinclair technology is also available in Timex/Sinclair computers 
under a license from Sinclair Research Ltd. 



THE $99.95 





■ Multi-dimensional 
string and numerical arrays 

■ Mathematical and scien- 
tific functions accurate to 
8 decimal places 
■ Unique one-touch entry 
of key words like PRINT, 
RUN and LIST 

■ Automatic syntax error 
. detection and easy editing 

■ Randomize function 
useful for both games and serious applications 

■ 1 K of memory expandable to 16K 

■ A comprehensive programming guide and 
operating manual 

The ZX81 is also very convenient to use. It 
hooks up to any television set to produce a clear 
32-column by 24-line display. It comes with a 
comprehensive programming guide and oper- 
ating manual designed for both beginners and 
experienced computer users. And you can use 
a regular cassette recorder to store and 
recall programs by name. 



Order at no risk.** 

We'll give you 10 days to try out the ZX81. If 
you're not completely satisfied, just return it to 
Sinclair Research and we'll give you a full refund. 

And if you have a problem with your ZX81 , 
send it to Sinclair Research within 90 days and 
we'll repair or replace it at no charge. 
Introducing the ZX81 kit 

If you really want to save money, and you 
enjoy building electronic kits, you can order the 
ZX81 in kit form for the incredible price of just 
$79.95.* It's the same, full-featured computer, 
only you put it together yourself. We'll send com- 
plete, easy-to-follow instructions on how you can 
assemble your ZX81 in just a few hours. All you 
have to supply is the soldering iron. 
A leader in microelectronics. 

The ZX81 represents the latest technology in 
microelectronics. More than 10,000 are sold 
every week. In fact, the ZX81 is the fastest selling 
personal computer in the world. 

We urge you to place your order for the 
ZX81 today. 
To order. 

To order, simply call toll 
free. Or use the coupon below. 
Remember, you can try it for 
10 days at no risk.** The sooner 
you order, the sooner you can 
start enjoying your own 
computer. 

Call toll free 800-543-3000. 

Ask for operator #509. 
In Ohio call: 800-582-1364; 
in Canada call: 513-729-4300. 
Ask for operator #509. Phones 
open 24 hours a day, 7 days 
a week. Have your MasterCard 
or VISA ready. 



These numbers are for orders only If you just 
want information, please write: Sinclair Research 
Ltd., 2 Sinclair Plaza, Nashua, NH 03061. 

•Pius shipping and handling. Price includes connector; for TV and cassette, AC adaptor, and 

FREE nnanuaj. 

"Does nol apply to ZX81 kits. 




NEW SOFTWARE: Sinclair has 
published pre-recorded pro- 
grams on cassettes for your 
ZX81. We're constantly coming 
out with new programs, so we'l 
send you our latest software 
catalog with your computer. 



16K MEMORY MODULE: Like 
any powerful, full fledged com- 
puter, the ZX81 is expandable. 
Sinclair's 16K memory module 
plugs right onto the back of 
your ZX8 1 . Cost is $49 .95, plus 
shipping and handling. 




To order call toll free: 800-543-3000 







Price* 








Ad Code 09RE 


Qty. Amount 




ZXSl 


$99.95 








ZX81 Kit 


79.95 








16K Memory Module 


49.95 








Shipping and Handling 


4.95 




$4.95 




MAIL TO: Sinclair Research Ltd., 
One Sinclair Plaza, Nashua, NH 03061 

N-snrip 




TOTAL 








AHrire>« 








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If you have put off 
learning more 
electronics for any 
of these reasons, 
act now! 



□ I don't have the time. 

□ High school was hard for me and 
electronics sounds like it may be 
hard to learn. 

□ I can't afford any more education. 

□ I have a family now. 

□ I'm here. You're there. I've never 
learned that way before. I'm not 
sure it will work for me. 

Read the opposite page and see how you can get started today! 



Be honest with yourself. Are 
the reasons really excuses? You 
already know enough about 
electronics to be interested in 
reading this magazine. So why 
not learn more? If you need 
encouragement, read on and 
see how excuses can be turned 
into results. 

You don't have the time. Be realistic. 
All you have in life is a period of time. 
Use it. Try to know more tomorrow 
than you do today. That's the proven 
way to success. CIE studies require just 
about 12 hours of your time a week, two 
hours a day. You probably do have the 
time. 

Electronics sounds like it may be hard 
to ieam. You already know something 
about electronics or you wouldn't be 
reading this. Now, build on that. CIE 
Auto-Programmed 8 Lessons help you 
learn. Topics are presented in simple, 
logical sequence. All text is clear and 
concise for quick, easy understanding. 
You learn step by step, at your own 
pace. No classes to attend. Nobody 
pressures you. You can learn. 
You can't afford any more education. 
Actually, you can't afford NOT to 
gain the skills that can put you ahead of 
the others. You know what inflation is 
doing to you now. Education — learning 
a skill — is an inflation-fighter that can 
be yours. If you are not able to pay full 
tuition now, CIE will lend you funds on 
a monthly payment plan. 
You have a family now. All the more 
reason why you have the responsibility 
to advance yourself. For the sake of 
your family. Do you want them to have 
what you had or have more than you 
had? The choice is yours. Electronics is 
a rewarding career choice. CIE can help 
you to get started on that career. 
You're there. We're here. How does 
CIE help you learn? First, we want you 
to succeed. You may study at home, but 
you are not alone. When you have a 
question about a lesson, a postage 
stamp gets you your answer fast. You 
may find this even better than having a 
classroom teacher. CIE understands 
people need to learn at their own pace. 
When CIE receives your completed 
lesson before noon any day of the week, 
it will be graded and mailed back the 
same day with appropriate instructional 
help. Your satisfaction with your 
progress comes by return mail. That's 
how CIE helps you learn. 



NOW, IF YOU AGREE CIE 
TRAINING CAN WORK 
FOR YOU, HOW ELSE 
CAN CIE HELP YOU? 

Cleveland Institute of Electronics is the 
largest independent home study school 
in the world that specializes exclusively 
in electronics. Although "big" does not 
always mean "best" it is evidence that 
CIE is a strong, successful institution 
with the people and resources to help 
you succeed. 




Step-by-step learning includes 
"hands-on training. 

The kind of professional you want to be 
needs more than theory. That's why 
some of our courses include the 
Personal Training Laboratory, which 
helps you put lesson theory into actual 
practice. Other courses train you to use 
tools of the trade such as a 5MHz 
triggered -sweep, solid-state oscilloscope 
you build yourself— and use to practice 
troubleshooting. Or a Digital Learning 
Laboratory to let you apply the digital 
theory that's essential today for anyone 
who wants to keep pace with electronics 
in the eighties. 




Your FCC License can impress 
employers. 

For some electronics jobs, you must 
have your FCC License. For others, 
employers usually consider it a mark in 
your favor. Either way, your License is 
government-certified proof of your 
knowledge and skills. More than half 
of CIE's courses prepare you to pass 
this exam. Surveys show that some 
80% of CIE graduates who take the 
exam are successful. 



Find out more! 
Today. Now. 

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coupon. 

You'll get a copy of CIE's free 
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For your convenience, we'll try to 
arrange for a CIE representative to 
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you may have. 

If you are serious about a rewarding 
career, about learning electronics or 
building on your present skills, your 
best bet is to go with the electronics 
specialists — CIE. Mail the card or 
coupon today or write CIE (please 
mention the name and date of this 
magazine), 1776 East 17th Street, 
Cleveland, Ohio 44114. 

This could be the best decision 
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Associate Degree 

Now, CIE offers an Associate in 
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"If you're going to learn 
electronics, you might as well 
learn it right!' 

John Cunningham 
Senior Technical Director 



■ CIE 




Cleveland Institute 
of Electronics, Inc. 



177 6 East 17 Eh Street. Cleveland, Ohio 44114 
Accredited Member National Home Study Council 



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21 



LETTERS 



Address your comments to: Letters, Radio-Electronics, 

200 Park Avenue South, New York, NY 10003 



DATABASE MANAGEMENT 
SYSTEMS 

I have just finished reading the June 1982 
issue of Radio- Electronics. Your article on 
database management systems was an in- 
teresting summary of available products and 
vendors, but I should like to correct a few 
oversights. 

First, Compco has had to move to a larger 
facility. I don't believe that the post office is 
forwarding our mail any longer (it's been a 
year), so I would appreciate having this letter 
published with our correct address. It is: 

Compco, 7110 W. Fond Du Lac Avenue, 
Milwaukee, Wl 5321 8. We can be reached by 
telephone through calling (414) 438-0610 or 
(414)438-8611. 

Secondly, Compco carries a wide variety of 
database management packages, for many 
different computers. Apple, Altos, and DEC 
are the principle lines, CP/M, MP/M, Apple 



DOS 3.3, Apple CP/M, and RT-1 1 are the 
principal operating systems that our products 
run under. We also carry a variety of word 
processing, scientific, and entertainment 
software and hardware. 
THOMAS M. PETERS, 
Compco, Sales Manager 

OPENING THE DOOR 

What a wonderful "opening of the door" to 
the world of electronics the simple building 
blocks described in "Hobby Corner," in 
Radio- Electronics, June 1982 provide! 

The beginner is generally confronted with 
completely enclosed "black boxes" that defy 
understanding. First encounters are most im- 
portant; and since most learning is through 
the eyes, the inner working parts should be 
exposed by removing all covers. 

Touching is another great avenue for learn- 
ing. (Beginners will soon be adjusting battery 



clips and switch tensions on their own.) 

As learning progresses, open-type 
potentiometers and transformers with visible 
windings may be added. Also, the name of 
each component may be lettered simply on 
each block, along with its schematic symbol. 
You cannot imagine how fast your young- 
ster can learn, or how importantly those be- 
ginning blocks can shape his or her life! 
GENE BRIZENDINE, W4ATE, 
Huntsville, AL 

DIGITAL THERMOMETER 

This is an addition to the digital ther- 
mometer article by Michael Ribgy that ap- 
peared in the February 1982 issue of Radio- 
Electronics. I have used this circuit on my 
MA1026 clock module to vary the brightness 
of the LED display automatically with 
changes in the room light. The circuit uses 
only three components, all of which are readi- 




•t 



ti 



opyright © 1982. ftktronbi. Inc. All nghts reserved . 133-1 



ly available, and I have had it in service for 
over a year. 




FIG. 1 

Figure 1 tells the story. As the room light 
goes down, the resistance of LDR1 (Radio- 
Shack No. 276-116) increases. At a given 
point, determined by the value of Rl, Q1 
begins to conduct. That lowers the voltage on 
pin 4, and dims the display. Use any low- 
leakage transistor for Q1 , with a gain (h ta ) of 
1 00 or more. Select the value of R1 to get the 
desired dimming action, and remember that 
raising the value of R1 will slow the dimming 
action. 

HERBERT DEAN, 
Orono. ME 



NIKOLA TESLA'S 
CONTRIBUTIONS 

In your comment on Vince Marasco's letter 
about Nikola Tesla ("Letters," Radio- 
Electronics, June 1 982) you pointed out that 



Mr. Marasco had failed to list any of the princi- 
ples relating to everyday things that nearly all 
of us now take for granted that Tesla dis- 
covered. 

The list is impressive: First, there is the AC 
motor. It is doubtful that there are any motor- 
driven devices in the home that do not use an 
AC motor, rather than the older DC units. Air 
conditioners, refrigerators, fans— all are built 
on Teste's principle that he developed for 
Westinghouse. 

Add to that his discovery in 1 890 of apply- 
ing high-frequency electricity to the body for 
deep heat treatment. Diathermy, in other 
words. 

Then there is the Tesla coii — an air core 
transformer with resonating primary and 
secondary coils. Such units are used to test 
the effects of high-frequency electricity on 
switches and regulating circuits in the utility 
industry. 

Marconi's patents on radio were upset by 
the U.S. Supreme Court, which ruled that 
they were an infringement on another's 
idea— Tesla. Robots, radar, and radio- 
controlled ships for military use, as well as the 
basic idea for a plane with vertical take-off 
and landing capabilities give you some 
idea— though really far from adequate— of 
the scope of that man's creative genius. 

To anyone interested in Nikola Tesla, I rec- 
ommend Margaret Cheney's book, an ex- 
cellent biography titled, Tesla, Man Out of 
Time. In spite of one or two technical faults, it 
is worth reading; you will understand why 
there are so many who rate Edison second to 
Tesla, without denying the worth of Edison's 
contributions. 

GEORGE deLUCENAY LEON, 
New York, NY 



SPEAKING OUT 

I can keep silent no longer' 

I'm an electronics buff, and have been re- 
ceiving Radio- Electron res for about a year. I 
am also currently subscribing to a number of 
other somewhat similar magazines, but have 
decided that the ony ones to which I shall 
renew my subscription are Radio- 
Electronics and The Audio Amateur. 

I consider Radio-Electronics to be by far 
the best electronics magazine on the market 
at the present time, and look forward to re- 
ceiving it each month. I cannot recommend it 
too highly! 

To date, I have built eight of the construc- 
tion projects that you have published. They 
were easy to complete, and all function as 
intended. I would like to compliment you on 
the clarity and completeness of your pro- 
jects — such that one does not need a high 
degree of electronics theory or expertise to 
build them, nor run into difficulty because of 
exotic or highly expensive components. I also 
applaud the fact that, to date, you have re- 
sisted the temptation to make Radio- 
Electro n ics i nto a co mp uter m agaz i n e ; th e re 
are a plethora of those available. Please con- 
tinue your emphasis on construction electro- 
nics with a broad-base appeal. 
PAUL T. KELLY, 
Fort Wayne, IN 



POCKET CALIBRATOR 

Gary McClellan's statement that the 
LM723N voltage regulator has more stable 
temperature characteristics than the 
LM723C ("Pocket Calibrator for Volts and 
Ohms," Radio-Electronics, June 1982) is 



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SIMPSON DIGITAL MULTIMETER SELECTION CHART 












Hand portable DMMs 
All 2x5.6x4.6". weight 1* lbs. 


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463 

Basic 
tow cost 
cordless 

unit 


461-2 

Low cost 
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461-2R 


462 


464-2A/2D* 


465-2A/2D* 

Auto and 
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1 amp 
range 


460-4A74D' 

Deluxe unit. 

Low power 

ohms, aux. 

analog meter, j 

10 amp 

range 


Featuret 


Deluxe unit with 
true RMS, pulse 
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hold, visual/ 
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ity Indication. 
£Black case 


True RMS 
responding 


Auto and 

manual 
ranging 


Low cost 

bench 

DMM With 

10 amp 

range 


Rmgei 


26: 


26 


26 


26 


23 


28 


27 


32 


Display 

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Basic 

Accuracy 

Power 

Source 

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LCD DigalogP 
display 


LCD 


LEO 


LED 


LED 


LED 


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LED 


0.1% 


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0.25% 


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9 V battery supplied, 
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S257 [ $200 


Rechargeable batteries and 
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S194 [""1234 | $244 


AC operation standard, 'AC/battery ver- 
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S290/*$338 |$403/*S453 ! S37B/'S431 



to 
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< 

24 



Choose the one that's best for you! Available at leading electrical/ 
electronics distributors worldwide. 

4ylttK\^M SIMPSON ELECTRIC COMPANY 

. ! t iTA»Vi{jn Ti~i A Katy Industries Subsidiary 
853 Dundee Avenue, Elgin, IL 60120 
(312)697-2260 • Telex 72-2416 • Cable SIMELCO 
IN CANADA: Bach-Simpson Ltd., London, Ontario 
IN ENGLAND: Bach-Simpson (U.K.) Ltd., Wadebridge. Cornwall 

CIRCLE 21 ON FREE INFORMATION CARD 



open to misinterpretation. The premium de- 
vice is the LM723. The relaxed-specifications 
version is the LM723C. The suffix "N" refers 
not to quality but to package type, in this case 
a dual-in-line plastic one. 

Thus, an LM723N would, indeed, be super- 
ior to an LM723CN, or any other LM723C 
type. Unfortunately, it has been my experi- 
ence that if one orders a 723N from advertis- 
ers in your Market Section, one will receive a 
723CN. Of course, in most applications for 
the hobbyist, the "C" version will be quite 
adequate. However, if an LM723N (or 
LM723H) is really preferred, as in Mr. McClel- 
lan's nice little project your readers may have 
to order it from one of the major electronics 
parts distributors. 
LAWRENCE WALLCAVE, 
Santa Rosa, CA 



THE I8M COMPUTER 

I have just finished reading your April 1 982 
issue, and noticed an article about IBM's first 
personal computer. In 1975, IBM was testing 
a rather heavy portable computer that was 
configured much like the Osborne 1. It had a 
non-removable keyboard, a small (perhaps 5 
x 6-inch) monitor screen, and used data cas- 
settes for loading. It was, I believe, the brain- 
child of Dick Doyle. 

Time and time again, we see IBM showing 
all the youthful vigor of a tortoise, and, in 
personal-computer hardware, they've shown 
it again, I think that's a shame, because I like 
:hem. 

ESSE THARIN, 
Tucson, AZ R-E 



ATTENTION 

SINCLAIR ZX81 

OWNERS!!! 

Here's an inexpensive little book 
(Programming With The ZX81 ) that 
tells you how to use the features of 
that ZX81 you recently bought, tt 
shows you programs that fit into the 
1K machine and are still fun to use. 
Learn how the random number 
generator works and use it to sim- 
ulate coin tossing and dice throwing. 
Look at the patterns the ZX81 
graphics can produce. Animated 
graphics are also covered and com- 
plete programs for games such as 
Lunar Lander and Cannon Ball are 
included. Seven information packed 
chapters in this quality book. Order 
your copy today. Price is $5.75 post- 
paid in the US. 

ELECTRONIC TECHNOLOGY TODAY INC. »sz 

P.O. Box 83. Massapequa Park, NY 11762 

□ Sand ma my copy & "Praflrimminfl WtRi Ths ZXflf 

□ Sand ma Ywr compSate caMon. 

Pries □« Book inchjdmg Postage ^ 75 

MV Stl1a Residsnls inciudfl Sales Tax 

TOTO. ENCLOSED 



Atkkoss— 
Of. 



-»P- 



THIS DEVICE MAKES 
ORDINARY TELEPHONES OBSOLETE 




dual size, 
f7"x5 1 A'x2%") 



The Freedom Phone® Cordless Telephone Model FF-3500 has more features than any ordinary 
telephone. But one ordinary feature is missing. 

There's no cord to tie you down. The compact handset measures 1 " x5Vs" x2W and weighs just 7 
ounces. So it's really easy to take or make calls anywhere within its operational range. That's upstairs, 
downstairs, In the front yard, backyard, at the neighbors, up the street, or down the block. 

Instead of going to the phone to talk, you take the phone with you. 

Buying a Freedom Phone Cordless Telephone is an intelligent move if you prefer the convenlen t over 
the conventional. But there's more to it than meets the eye or ear. 

Designed and built exclusively for the Electra Company, makers of Bearcat® Scanners, the Freedom 
Phone 3500 provides crisp and clear cordless calls. An audible tone and pulsing light confirm dialing. The 
touch of a button automatically redials the last number entered. 

The Freedom Phone Cordless Telephone is as easy to install as it is to use. Its attractive and compact 
base station plugs into your existing phone line and electrical outlet. 

If the idea of using a Freedom Phone Cordless Telephone has a nice ring to it, get up, walk to your 
obsolete telephone, and call 800-428-4315 (800-382-1076 in Indiana). You'll learn more about the Model 
FF-3500 and get the name of the nearest Freedom Phone Dealer. 

THE FREEDOM PHONE CORDLESS TELEPHONE. 

[Ejectis^ Electro Company 
DMsion of Masco Corp. of Indiana • 300 East County Line Road ■ Cumberland, Indiana 46229 • International Business Office - Suite 102, 1S2S Swift • North Konsas City, Missouri 641 16 

© 1981 Wasco Corp. of Indians 
CIRCLE 19 ON FREE INFORMATION CARD 



CO 

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ro 



25 



EQUIPMENT REPORTS 



Sencore 

Model SC61 

Waveform Analyzer 





PRICE/ 

/VALUE 



CIRCLE 106 ON FREE INFORMATION CARD 



FOR QUITE A FEW YEARS NOW, SENCORE 

(3200 Sencore Drive, Sioux Falls, SD 
57107) has been manufacturing "an- 
alyzers" — composite instruments that 



are useful for a wide variety of electronics 
testing and measuring. One of their new- 
est products is the model SC6J waveform 
analyzer. Whether you're working with 



analog or digital circuitry, you'll find a 
great many applications for this device no 
matter what kind of electronics work you 
do. It is really a quite versatile instru- 
ment, as you'll soon see. 

The model SC61 has two main sec- 
tions. One is a dual-trace scope that can 
be used with waveforms of up to 100 
MHz and voltages from 2 millivolts to 2 
kilovolts. The unit's wide bandwidth (60 
MHz), which is useable right up to the 
upper frequency limit, can come in very 
handy when working with high-speed di- 
gital circuitry. All of the standard features 
are there, including triggered sweep, a 
special delayed sweep mode called the 
delta mode (more on that later), and sync 
separators. The other section of this in- 
strument is a built-in digital voltmeter 
with a 6-digit LCD display. The DVM 
display, incidently, is located right across 
continued on page 30 



w 
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Your guide to the 

world of microprocessors. 

The Micro-Professor™ -a low cost tool for 

learning, teaching and prototyping. 



Here in one attractive package 
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The Micro-Professor is a 
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system whose extensive teaching 

* Z80 is a trademark of Zilog Inc. 



manual gives you detailed 
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gram code. A superb learning 
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But the Micro-Professor is 
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The standard 2K bytes of 
RAM is expandable to 4K, 
and the standard 2K bytes of 
ROM can be increased to 8K. 

All this plus a built-in 
speaker, a cassette interface, and 



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sockets to accept optional 
CTC/PIO. Bus is extendable. 

As well as being an exciting 
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SSB-MPF 

Speech 

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Board $129 

A 
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In U.S. and Ciiudi null to: 
Multitech Electronics Inc. 
195 West El Camino Real 
Sunnyvale, CA 94086 
California Tel. (408) 773-8400 
Elsewhere (800) 538-1542 



Outs ids ol North Amaritt mail U: 
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outputs 



' Three-step attenuator plus 
vernier control 

■ internal linear and fog sweeps 

■ Tone-burst output is front-panel or 
externally programmable 



L^J 



fBEE HOt>'- 6 

800-223 



TOIAJ 



-0474 



THE TEST EQUIPMENT SPECIALISTS 



ADVA 



54 WEST 45th STREET. NEW YORK. N.Y 10036 212-687-2224 




EQUIPMENT REPORTS 



continued from page 26 



the top of the scope screen for easy read- 
ing. Pushbuttons arc used for case of op- 
eration. You can read the peak-to-peak 
voltage of any waveform on the screen 
and then simply push a button and read 
the DC level in the circuit (more on that 
later), or push another button and read the 
frequency of the displayed signal. 

All of the circuitry of the model SC6! , 
aside from the manual scope controls, is 
microprocessor-controlled. That microp- 
rocessor monitors the vertical and hori- 



zontal circuits at all times; to make any 
kind of measurement, just push a button 
and the microprocessor does the rest. It 
controls the digital readout, and also 
"lights" one of the 12 display an- 
nunciators that tell you what you're read- 
ing, and where (which channel). The dec- 
imal point is automatically set for all 
ranges and functions. 

Getting back to the scope, the time- 
basl-preq switch controls the horizontal 
sweep. That switch has 19 calibrated 
ranges. Those are setup in the usual 1-2-5 
sequence and range from 0. 1 micro- 
second to 100 milliseconds; a frequency 
scale is also provided. That switch is also 
used to place the unit in the video-preset 



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mode that is used to analyze video sig- 
nals. In the video-preset mode, pushing 
one of two buttons will display either two 
vertical fields or two horizonal lines. The 
sync here is very steady due to the use of 
special sync- separators. The horizontal 
position control positions the trace; pull 
the knob and the waveform is expanded 
10 times. While you could take an analog 
reading of time or frequency from the 
sweep-setting and the graticule, if you 
want to, it is much easier and faster to use 
the frequency readout for that, and the 
readings will be much more accurate. The 
readout is not affected by the setting of the 
timebase switch; whether you display one 
cycle, or several, the frequency will be 
picked off and read out by the micro- 
processor. 

The sweep trigger circuits can be used 
on either channel, the AC line, or external 
trigger. A level control selects trigger- 
ing on either positive- or negative-going 
edges of the displayed signal. When an- 
alyzing video signals, the peak-to-peak 
voltage of cither horizontal or vertical 
waveforms can be measured by adjusting 
the level control. One thing that can 
cause problems in horizontal waveforms 
is the presence of some of the vertical 
sync; that also can be eliminated by 
adjusting the level control. The pres- 
ence of the vertical sync can confuse the 
microprocessor, which will throw the 
peak-to-peak voltage readings off. 

The unit has special sync-separator cir- 
cuitry that helps in eliminating that confu- 
sion. That circuitry triggers on the ver- 
tical or horizontal pulses present in almost 
all TV signals. However, the manual 
mentions that if you're trying to read the 
output of a stage like the color-bandpass 
amplifier, where sync pulses are removed 
by the filtering action of the circuits, you 
may have instability. To eliminate that 
problem, simply hook the probe of the 
other channel to some point that does 
have sync, such as the video- detect or out- 
put, etc. Now, trigger the sweep with the 
pulses from that channel. 

Every one of the tests mentioned, as 
well as others we'll look at later on, can 
be done by just hooking up a probe and a 
ground lead. When that is done, just 
about anything about the circuit can be 
measured simply by pushing the appro- 
priate buttons. Incidently, while two of 
the probes supplied look like the standard 
hook-tipped probes, they are not. They 
are, instead, 10:1 low-capacitance pro- 
bes; each has a special "separator" cir- 
cuit built into it. That circuit lets you read 
waveforms and DC voltages at the same 
time! A separate, isolated, DC connector 
on the probe is plugged into a jack labeled 
dcv. The DC component is picked off by 
that separator circuit before the scope in- 
put and fed to the microprocessor, which 
does the rest. Because of that, both the 
reading displayed on the meter and the 
trace displayed on the scope are correct. 



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The scope settings, as we said before, do 
not affect the meter readings in any way. 
In addition to the 10:1 low-capacitance 
probes, the unit is also supplied with a 
direct-reading DC probe and a 48-inch- 
long ground lead. 

Among the features that sets this unit 
apart is its special delayed sweep mode 
that is called the delta-measurement 
mode. That mode lets you measure the 
peak-to-peak voltage, frequency, or per- 
iod of only the section of the waveform 
that you are interested in. It can be set for 
any portion of the waveform using the 
A beg in and the A end controls. Those 
controls position the beginning and end of 
a bright ' 'bar' ' on the display. The part of 



the waveform within the span of that bar 
is the only part that is measured when the 
scope is in the delta mode. Trigger con- 
trols work in the usual manner in that 
mode. 

Among other things, the delta mode is 
useful for reading the frequency of only 
one cycle. If you have more than one 
frequency present, such as with a mod- 
ulated waveform, you can read any one 
by isolating that part of the waveform 
within the delta bar. 

To try out the delta mode, we used it to 
troubleshoot a DC supply in a solid-state 
television set. That supply's output wave- 
form showed some unusual symptoms, 
but ones that were obviously caused by 



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feedback. On what should have been a 
clean DC signal, we found tiny high- 
frequency "bursts;" the frequency of 
those bursts turned out to be about 40 
kHz, the ringing frequency of the flyback 
pulse. As the DC supply came from the 
flyback, that seemed to indicate that the 
DC supply was not adequately filtered. 
From that point it was relatively easy to 
track the problem down to an open filter 
capacitor in the DC line; that open capaci- 
tor was allowing the ringing to get into the 
signal circuits. 

This instrument is a real pleasure to 
use. All the controls are grouped by func- 
tion and channnel for maximum efficien- 
cy. The built-in digital display eliminates 
the need for graticule counting, allowing 
you to analyze a waveform quicker, and 
more accurately, than ever before. All 
this sophistication comes at a price, of 
course, as the model SC6I lists for 
$3275. 00. including probes. However, if 
you do a lot of work with a scope, and 
consider the time and eye strain this in- 
strument will save you, the price is well 
worth it. R-E 



McKay/Dymek 
General Coverage 
Receiving System 




CIRCLE 1 07 ON FREE INFORMATION CARD 



McKay/Dymek DR-44-6 






OVERALL 
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ALTHOUGH A LARGE PERCENTAGE OF 

McKay/Dymek (Post Office Box 5000, 
Department B, Claremont, CA 91711) 
products are for shipboard use on vessels 
of foreign registry, many items in their 
catalog are of interest to serious short- 
wave/longwave listeners as well. One 
such system consists of the DR44-6 re- 
ceiver (shown), the DP4044 preselector, 
and the DSIII audio processing speak- 
er. We'll look at each one of those in- 
dividually, with the main emphasis on the 
DR44-6 receiver. 

The DR44-6 receiver 

Designed to fit in a standard 19-inch 
rack-panel mount, the mode! DR44-6 is a 



32 



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general -coverage frequency-synthesized 
receiver that displays the received fre- 
quency on six large (0.5 inch) LED 
characters with an accuracy of 100 Hz. 

The rear panel features a variety of 
connectors for increased flexibility in 
custom installations. Those include a 
high-impedance audio output with an 
associated level control, a mute jack, a 
50-ohm BNC antenna connector, a low- 
impedance speaker output and a separate 
600-ohm line output (both available from 
spring- loaded terminals), and an IF out- 
put (455 kHz) for a panoramic display or 
teletype converter. 

Receiving modes include AM, SSB, 
CW, and RTTY. A separate rot ary switch 



allows selection of either 4- or 8-kHz 
bandwidth filtering of the upper/lower 
sidebands. Two additional unoccupied 
positions can accommodate the installa- 
tion of optional filters by the user. 

A noisc-limiter circuit provides 
attenuation of pulse-type interference on 
any mode except AM. The AGC decay 
rates (fast or slow) may be selected or 
defeated entirely. 

Frequency is selected through the com- 
bined use of 5 rotary controls, each add- 
ing or subtracting a frequency interval on 
the display (10 MHz, 1 MHz, 100 kHz, 5 
kHz). The 5th control is variable, provid- 
ing infinite resolution of the last 5 kHz. 

Frequency displacement on upper and 



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lower sidebands is compensated in the 
readout so that the user will see the actual 
window frequency (suppressed carrier) 
without the mental gymnastics frequently 
necessary with other receivers. 

Our lab tests 

The DR44-6 was used with a 135-foot 
dipole antenna and in conjunction with its 
companion DP4044 preselector. 

We found little advantage in using the 
preselector for the vast majority of appli- 
cations; the preselector would best be 
used when there is a nearby source of 
strong RF interference. 

Thermal and mechanical stability of 
the receiver were excellent. Little or no 
frequency drift was observed during rea- 
sonable periods of listening time after ini- 
tial warmup. Frequency coverage for the 
DR44-6 is specified as 50 kHz through 
29.7 MHz. Actual reception over that fre- 
quency range was confirmed. 

RF sensitivity was excellent, certainly 
equivalent to or greater than that of most 
competitors. 

"Birdies" are spurious signals caused 
by the frequency synthesizer. They are 
always present on receivers that use a 
frequency synthesizer to generate the lo- 
cal oscillator signal. While also present 
on the DR44-6, none was found too loud 
to detract from the readability of incom- 
ing radio signals. Two extremely loud 
birdies appeared to have been generated 
by the BFO, and were heard on 10 and 20 
MHz; but those two frequen- 
cies arc occupied by full-carrier WWV, 
and they disappeared in the AM mode. 

Image rejection is specified as 70 dB , 
and in our lab tests images were certainly 
no problem. Additional specifications in- 
clude cross-modulation and intermodula- 
tion suppression of 65 dB (referred to 1 
microvolt) and RF blocking of 100 dB 
(also referred to 1 microvolt). A 25-dB 
5 -kHz audio-notch filter removes any 
heterodyne interference from adjacent 
channel broadcasts. 

A 2-MHz high-pass filter provides use- 
ful suppression of interfering signals 
from the AM broadcast bands and below 
when the receiver is being used only for 
shortwave reception. RF signal attenua- 
tion may be used to reduce overload from 
strong signals. 

Two watts of audio output intoa4-ohm 
load impedance is available at the rear 
panel as well as a 1-volt RMS line output 
(5,000-ohms impedance). AC power re- 
quired is 120 or 240 volts, 50/60 Hz (30 
watts) . 

The internal circuitry is very clean and 
well laid out, featuring 56 IC's, 31 
FET's, 20 transistors, and 66 diodes. 

The accompanying instruction manual 
is well written and comprehensive, pre- 
senting descriptions of each portion of the 
receiver's circuitry, including both com- 
ponent layout and schematic drawings. 
continued on page J 04 






CIRCLE 23 ON FREE INFORMATION CARD 



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RADAR TRANSMITTERS. By G. W. 

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MODERN ELECTRONIC CIRCUITS 
REFERENCE MANUAL. By J. Mar- 
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DIGITAL HARDWARE DESIGN By J. 

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491/321 Pub. Pr., $33.00 Club Pr. $26.00 



INTRODUCTION TO THE THEORY 
AND DESIGN OF ACTIVE FILTERS. 

By L. P. Huelsman and P. E, Allen. 
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DIGITAL CIRCUITS AND MICRO- 
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.J 39 



SATELLITE/TELETEXT NEWS 



GARY ARLEN 

CONTRIBUTING EDITOR 



WIRELESS 
CABLE PLAN 



Urbanet, a multi-channel microwave hybrid service that can be used for teletext, 
data transmission, pay-TV, and other entertainment services, is being proposed by 
Microband Corp, of America, the nation's largest operator of Multipoint Distribution 
Service (MDS) stations. Microband's proposal for "wireless cable" would create up to 
14 video channels In the top 50 U.S. cities. The channels would operate in the 2500 
MHz band, and would be first cousins of the MDS pay-TV services now offered in many 
markets in the 2160 MHz range. The Urbanet arrangement would accommodate na- 
tional and local transmissions in a variety of modes: one-way. two-way, interactive, 
and asymmetrical. For example, the broadband MDS channel could be used to trans- 
mit video programming; an asymmetrical variation could be used to download video- 
games or for electronic mail. 

For services requiring two-way or interactive capability, the telephone will be used in 
conjunction with value-added data communications networks. By augmenting current 
software and data-storage capabilities, services can be developed to handle teletext 
and home banking. The Microband plan comes in response to a long-simmering FCC 
study about reallocating the 2500 MHz band that is now underused as an educational 
TV band. 



HIGH- 
DEFINITION TV 



High-definition television (HDTV), with 1 125-line video resolution, stereo sound, wide- 
screen pictures, and other enhanced features, seems to be moving ever closer to 
reality — and satellite distribution will be a major factor in its development. CBS and 
Japanese-TV network NHK recently demonstrated their latest refinements of HDTV, 
along with a hint that the service could begin in less than five years on a limited basis. 
Because of its sizeable spectrum demands — about 30 MHz-per-channel (five times the 
bandwidth of conventional TV)— HDTV will probably be used for special purposes. Di- 
rect-broadcasting satellites (DBS), cable-TV, and home-videocassette/disc distribu- 
tion are possible, because bandwidth limitations are not a problem as they are on cur- 
rent broadcast-TV systems. However, engineers are now working on band width -com- 
pression systems to bring down the spectrum requirements for HDTV. 

Satellite service is a high priority because a DBS transmission of a high-definition TV 
signal would offer theater-quality video projection. The 1125-line resolution will pro- 
vide picture quality at least five times better than today's TV signal — richer colors, 
higher resolution, and better contrast. The 3x5 screen ratio (compared to today's 
3^4 ratio) provides wide-screen capabilities. HDTV also offers Hollywood studios a 
new opportunity to produce movies directly as electronic cinema, rather than shoot on film 
and then transfer to videotape. 



TEXT VIA 
SATELLITE 






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o 

EC 

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UJ 

o 

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< 

DC 

40 



Text and data services will be transmitted nationwide via subcarriers on National Public 
Radio's transponders aboard Westar starting late this year. The project is part of public radio's 
effort to find new financial sources to support its non-commercial audio programming. 
According to this plan, the national satellite feed will be transmitted in hundreds of communit- 
ies by local public radio stations, again using subcarriers on their standard broadcast signals. 
In many cases, the local stations will also insert additional data aimed solely at receivers in 
their communities. 

Data will be transmitted using an SCA (Subsidiary Channel -Authorization) that is piggy- 
backed to an audio circuit. Each signal will carry an identifying code, and customers will be 
equipped with an addressable receiver to pick up the data. Customers would only be 
permitted to receive material designated for their specific decoder. Initially, most receiver 
locations would plug their decoders into hard-copy printers, but the data could also be 
displayed on a video screen. 

A new organization, Information Network Corp. (INC) has been set up by NPR and a 
Washington-area company called National information Utilities Corp. that will develop data- 
bases and services for the network, including videogames, shopping information, computer 
information, and business information, INC expects to deliver services almost entirely to 
business customers. The plan, however, is one of a growing number of projects seeking to 
piggy-back auxiliary services into the scarce satellite circuits. R-E 






just moved down in 



Make your move today. 

To top quality professional 

test equipment— Philips. 

Alt over the world Philips produces 
the test that more people trust. 
That's because the same superior 
engineering and ergonomic prin- 
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digital storage scope can be found 
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We put more into every scope 
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More precision. More rock-solid ■ 



quality. So you get more. And now 
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Philips PM3207 

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• B-invert • Triggering from A or B 
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D PM6667 120MHz High Resolution Counter 

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CIRCLE 13 ON FREE INFORMATION CARD 



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Far more information call 
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and New Jersey. In New Jersey call 
collect (201) 529-3800, or contact 
Philips Test & Measuring Instruments, 
Inc., 85 McKee Drive, Mahwah, NJ 
07430. In Canada: 2375 Steeles Ave. 
W., Unit 126, Downsview, Ont., Can. 






NEW IDEAS 



Electronic Thermometer 



HERE IS AN INEXPENSIVE ELECTRONIC 

thermometer than can be built in just one 
evening. It is capable of measuring 
temperatures over a range of from - 30°F 
to + 120°F. 

The circuit is shown in Fig. 1 ; its opera- 
tion is fairly straightforward. A diode- 
connected 2N3904 transistor forms a vol- 
tage divider with Rl. The transistor is 
used as the temperature sensor and, for 
best results, should be connected to the 
rest of the circuit using twisted wire as 
shown. As temperature increases, the 
voltage drop across the transistor changes 
by approximately — 1.166millivolts-pcr- 
°F. As a result, the current at pin 3 of IC1, 
a 741 op-amp with a gain of 5, decreases 
as the temperature measured by the sensor 
increases. 

A second 741 op-amp, IC2, is con- 
figured as an inverting amplifier. Since 
pin 3 of that IC is grounded, pin 2 is at a 
virtual ground and the sum of all currents 
into that pin must be zero. Resistors R5 
and R6 are used to calibrate the circuit. 
Once R6 is adjusted (more on that later), 
the current flow through those resistors 
will be constant. At a temperature of 
about — 30°F, the current through R4 
(that resistor is formed by connecting a 
910- and a 1600-ohm resistor in parallel) 
should equal the current through R5 and 
R6. 

At higher temperatures, the current 
through R4 will be less than the current 
through R5 and R6. Since the sum of the 
currents at pin 2 of IC2 should be zero, 
current will be drawn from the output (pin 
6) of that IC to offset the difference. That 
current must pass through Ml, and the 



amount of current drawn is, of course, 
measured by the meter. As the relation- 
ship between the amount of current drawn 
and the measured temperature is linear, it 
is relatively easy to calibrate the meter to 
indicate measured temperature. 

If the temperature goes below - 30 q F a 
reverse current will be generated. As that 
reverse current is undesirable, its flow is 
prevented by inserting D I into the circuit 
as shown. 

Calibration is also straightforward. 
When properly done, a temperature of 
— 30°F will result in a meter reading of 
milliamps, while a temperature of 120°F 
will result in a meter reading of 1 mil- 
liamp. Divide the scale between those 
points into equal segments and mark the 
divisions with the appropriate cor- 
responding temperatures. Note that di- 
viding the scale into more parts will result 
in greater accuracy; if you divide it into 
150 equal segments, for instance, each 
division will equal one degree. The 
calibration is completed by placing the 
sensor in an environment with a known 
temperature, such as an ice-point bath. 
The ice point of water is approximately 
32°F. That is the temperature at which 
water and ice can co-exist in the same 
container. To prepare the bath, place 
water and ice in a large glass beaker or 
similar container, wait a few minutes for 
the temperature of the bath to stablize, 
and verify that the temperature is indeed 
32°F using another thermometer that is 
known to be accurate. Then, simply place 
the sensor in the bath and adjust R6 until 
you get the correct meter reading. 
—David McNeill R-E 



OK 



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T*< I NIK 

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-<*VOL"TE> 



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W---*M- B ^ 






FIG. 1 



NEW IDEAS 

This column is devoted to new ideas, 
circuits, device applications, construc- 
tion techniques, helptul hints, etc. 

All published entries, upon publica- 
tion, will earn $25. In addition, Panavise 
will donate their mode! 333— The Rapid 
Assembly Circuit Board Holder, having a 
retail price of $39.95. It features an eight- 
position rotating adjustment, indexing at 
45-degree increments, and six positive 
lock positions in the vertical plane, giving 
you a full ten-inch height adjustment for 
comfortable working. (See photo below.) 




I agree to the above terms, and grant 
Radio- Electronics Magazine the right 
to publish my idea and to subsequently 
republish my idea in collections or com- 
pilations of reprints of similar articles. I 
declare that the attached idea is my 
own original material and that its publi- 
cation does not violate any other copy- 
right. I also declare that this material 
had not been previously published. 



Title of Idea 



Signature 



Print Name 



Date 



Street 



City 



State 



Zip 



Mail your idea along with this coupon 
to: New Ideas Radio- Electronics, 
200 Park Ave. South, 
New York, NY 10003 



42 



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• 

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Adjustable current limiting 
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Power supplied: \ 

1 3 V or 5 V. Measure circuit 

adjustable voltage #1 



Measure circuit 
voltage #2 



(324.95 



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Up to 7.5 amp. at each voltage- 



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CIRCLE 8 ON FREE INFORMATION CARD 



Hitachi V202 and 
V-352 Dual Trace 
Oscilloscopes 

When you get exceptional capa- 
bility per dollar, that's superior 
cost-performance. And that's 
the 35 MHz Hitachi V-352 and 
the 20 MHz Hitachi V-202 dual 
trace oscilloscopes. 

Proof? Just skim these fea- 
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starters, both scopes have a 2- 
year limited warranty. And 
then there are features like 
square CRT's with internal 
graticules, vertical sensitivity 



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plifier of 8 divisions or more. 
Each scope features front panel 
X-Y operation, 10X sweep mag- 
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low vertical drift. For ease of 
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controls are grouped into 3 
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How do we build in all that 
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Chalk it up to two decades of 
oscilloscope design experience 
and some of the most modern 
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Hitachi V-352 and V-202 are 

CIRCLE 14 ON FREE INFORMATION CARD 



stocked by your authorized 
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Ask for a demonstration and 
see more performance than you 
expected for less than you 
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the measure of quality 







HITACHI 

Hitachi Denshi America, Ltd. 

175 Crossways Park West 
Woodbury. NY 11797 
(516)921-7200 



\£>u'll recognize the name... 
appreciate the quality 





ROBERT GROSSBLATT 

Ml UK Al I I ( HNOl i Hil II \S C1R4 l« N 

tremendously over the past 20 years So 
much m> that the consumer now has in- 
struments available to him that at one lime 
could only be found in hospitals. One 
such instrument. .1 machine 10 monitor a 
heart rate, used to occupy an entire room 
and required a sizeable endow ment U> 
buy: now you can build one thai runs on 
batteries for under a hundred dollars. 

The Hcart-a-Matic described here 
gives a digital readout of your heart rate 
and can be built from readily available 
parts: 11 features both an audible and a 



Design considerations 

There are two basic problems thai ha\ c 



Heart Rate Monitor 

Knowing your heart rate and how it varies under different 
circumstances can give you an idea of your physical 
condition. Build the Heart-a-Matic and keep track of the 
state of your health and fitness. 



.11 be overcome in designing a reliable 
heart-rate monitor. The first is thai each 
heartbeat is actually made up of several 
beats; the second is that the heart is noi 
crystal-controlled — even a healthy hear) 
heats somewhat irregularly. 

I The heart is a four-chambered pump 
j consequently each heartbeat is eom- 
sed of several parts (everyone is lamil 
with the "lub-dub" heard through a 
thoscope). Figure I shows the various 
mponents of a heartbeat, the llcart-a- 
atic is designed to integrate the "F" 
d "T" portions of the waveform with 
; -R" portion. 
Even during rest, the rate at which the 
an beats varies: irregularity between 
ats is a natural characteristic of the 
heart. Several beats have to be sampled 
and averaged to provide a result thai has 
arij useful meaning. The Heart-a-Matfc 
heart-rate monitor uses an eight-beat 
sample to obtain an average reading. That 
number of beats was chosen as .1 good 
middle ground to minimize irregularity, 
■ '» 'he one hand, and to provide reason 
ile response-time, on the Other 
■-mereialh available machines 
multi-beat samples and update 
i end of each sampling period. 
ie Hearl-a-Matic. however, gives a 
running average. In other words. 
whenever it adds a new heal to its sample. 




TIME 

FIG. 1— THE PARTS OF A HEARTBEAT. THb 
Heart-a-Matlc Integrates the P and T portions 
with the R portion. 

it drops the first beat of the sample. Con- 
sequently, it's able to update with each 
beat and still give a meaningful readout. 

How it works 

As shown in Fig. 2, the Heart-a-Matic 
is composed of eight sections. A com- 
plete schematic of the device is shown in 
Fig. 3. The sensor, IC24, is an FPA104 
infrared emitter- sensor combination in 
one housing. The two elements are side 
by side and there is no direct way for the 
radiation from the emitter to be seen by 
the detector, because they are separated 
by part of the case. The sensor is designed 
to be placed against a person's finger. The 
IR (Mrafled) radiation emitted by the 
LED in IC24 penetrates the outer skin- 
layer and is reflected back to the detector. 
As the heart beats, a new volume of blood 
is pumped into the finger and changes the 
amount of infrared light reflected back to 
the photo-transistor. That change in 
blood density (and, consequently, in re- 
flected IR) is used by the Heart-a-Matic to 
determine the heart rate. 

The input amplifier, composed of Ql 
and IC1, has two main jobs. It amplifies 
the weak signal from the detector, and 
integrates the several components of the 
heartbeat into one pulse. The waveform 
emerging from the output of IC1 , howev- 
er, is far from being a clean single pulse. 
Even though the peaks and valleys of the 
heartbeat have been smoothed out, the 



pulse still has to be conditioned before it 
can meet the somewhat snobbish square- 
wave requirements of the digital circuitry 
that will process it later. That is a problem 
with any system that combines digital and 
analog techniques. While digital systems 
require strictly "yes" or "no" answers, 
the analog world usually provides just 
"maybes." 

The conditioning circuit, consisting of 
Q2 and IC2, squares the wave presented 
to it by IC 1 and raises its voltage level so 
it can be reliably detected by IC2, a 555 
configured as a monostable multi- 
vibrator, or pulse generator. Capacitor 
C8 and resistor R9 give the output pulse 
of the 555 a width of about 100 mil- 
liseconds. That serves two purposes. 
First, it insures that the high level of the 
pulse will be seen as a logic one by the 
digital circuitry that follows and, second, 
it helps eliminate the "maybes" of the 
analog world. Once the 555 is triggered, 
it ignores all other signals for 100 mil- 
liseconds. 

Should some signal ambiguity still 
manage to emerge from the analog por- 
tion of the heart-rate monitor, the first 
part of the digital portion should take care 
of it. Integrated circuit IC3-a is a Schmitt 
trigger set up as a half monostable with an 
output-pulse width of about 20 mil- 
liseconds, That signal is one of the two 
that control the interlock portion of the 
circuit made up of the three other nand 
gates of IC3 and IC5. A set-reset latch 
formed by IC3-b and IC3-c controls the 
calculation of the heart rate started by 
each heartbeat detected. 

When a positive pulse appears at the 
output of IC3-a it causes the output of the 
latch to go — and remain — high. That out- 
put is inverted by IC3-d and presented, 
through inverter IC22-f , to the clock input 
of IC21, a 4017 decade counter. Each 
pulse will make one of that IC's outputs 
go high in sequence. 

We are sure of starting with number 
one because CI 8 performs a power-on- 



SENS0R 



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DC 

46 




AMPLIFICATION 
AND 

CONDITIONING 






















BEEP 


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GENERATOR 


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SPEAKER 




SEQUENCE 
CONTROL 






COUNTER 

AND 
DISPLAY 














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TIMEBASE 

AND 
RATE CALCULATION 










P0WEH SUPPLY 

AND 
LOW-BATTERY WARNING 



FIG. 2— THE HEART-A-MATIC Is made up of eight main sections as shown In this block diagram of the 
device. 



reset function. That means that IC2 1 will 
start with its first output at a logic-high 
and will then clock along with incoming 
heartbeats for eight beats, at which point 
it will reset back to one. That happens 
because the ninth output (which, coin- 
cidentally, is also pin 9) is also connected 
to the reset pin. The outputs of the IC2 1 
are connected in successive pairs to 
IC20's 2-input nor gates. As a result, we 
have repeating sequential logic ones that 
are used in the section of the heart-rate 
meter that measures the period and calcu- 
lates the heart-rate frequency. 

Integrated circuit IC23 and its associ- 
ated components provide an extremely 
accurate source of 60-Hz square waves 
that are counted by IC16-IC19, 4040 bin- 
ary ripple counters. Each of the 4040' s is 
connected to the "D" inputs of a 4508 
(IC12-IC15) configured as 3-state eight- 
bit hold-and-follow latch. 

When a heartbeat is detected, one of 
the outputs of IC20 goes high and causes 
two things to happen. The first is that its 
associated 4508 is enabled, and the data 
present at that moment at its "D" inputs 
is stored in the latch and presented at its 
"Q" outputs. The second thing that hap- 
pens is that an inverter (a section of IC22) 
set up as a half-monostable outputs a posi- 
tive pulse, lasting about 70 mic- 
roseconds, that resets the 4040 to zero. 
The counter immediately starts counting 
again; but the latch is now disabled and it 
ignores the changing data at its inputs. 
The period of each heartbeat is counted at 
a 60-Hz rate and appears on the data bus. 

Next comes a bit of arithmetic. Since 
the device knows the period of the heart- 
beat, it now has to calculate its frequency. 
Those are reciprocals of each other and 
the form of the calculation that has to be 
performed is also simple. Sixty Hz (cy- 
cles-per-second) times 60 (seconds-per- 
minute) equals 3600 cycles-per-minute. 
The number of beats per minute is there- 
fore the number of cycles per minute di- 
vided by the number of cycles per beat. 
Since we are using a period of eight heart- 
beats, the magic number becomes 28,800 
(8 x 3600). The division is carried out in 
two ways. The first way is sneaky and the 
second is interesting. 

The sneaky way is to ignore the two 
least-significant outputs of the 4040's. 
By doing that we immediately divide the 
count by four. That also gives us the 
advantage of smoothing out any "bob- 
ble" in the circuitry by dropping the two 
least-significant figures, which is where 
it would show up. All we have to do now 
is divide by 7200 (28.800 4- 4), and the 
way that is done is one of the most in- 
teresting features of the Heart-a-Matic. 
The secret lies in an often overlooked, 
frequently misunderstood, and extremely 
useful type of IC — the rate multiplier. 

There are two types of rate multi- 
pliers — binary and decimal. The differ- 
ence between them is much the same as 




FIG. 3SCHEMATIC DIAGRAM of the Heart-a-Matic. The device is built on six separate PC boards. 

$ see l baawaidas 



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or. 

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g 

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the difference between a counter such as 
the 4520 that counts strictly in binary and 
its companion, the 4518. that counts in 
BCD (Binary-Coded Decimal). Since 
BCD isn't needed by this part of the 
Heart-a-Matic, the choice is the 4089, a 
binary rate-multiplier (IC9 and IC10). 

The 4089 has two types of outputs. The 
First, which we'll discuss shortly, is l /ih 
the input frequency; if a 16-kHz signal 
were applied to the input, the output 
would be 1 kHz. The second output is 
"programmable" and is equal to '/i& the 
frequency applied to its clock input multi- 
plied by whatever number is applied to its 
binary inputs. For example, if the input 
frequency is 16 kHz, and a binary four is 
presented to the binary inputs, the 4089 
will output a frequency of 4 kHz. Un- 
fortunately, a rate multiplier will not al- 
ways do exactly what you expect it to — 
output a number of pulses that is always 
an average of '/in the input frequency 
multiplied by the input number. While the 
example presented above works out very 
nicely, the rate multiplier may have to 
work with a frequency of 1 7 kHz as well . 
Since that figure is not evenly divisible by 

PARTS 
All resistors 1 /t-watt, 5% unless other- 
wise noted 

R1— 270 ohms 

R2, R4, R1 1 , R13, R39, R41 , R43, R45— 
10,000 ohms 

R3. R46— 470,000 ohms 

R5, R6, R35— 1 megohm 

R7, R31 , R33— 390 ohms 

R8, R9— 30,000 ohms 

R10, R14, R38, R40, R42, R44— 100,000 
ohms 

R12— 12 ohms 

R15, R24-R26, R29, R36— 1000 ohms 

R16-R22, R27— 160 ohms 

R16-R22, R27— 160 ohms 

R23— 15 Ohms 

R28, R32— 22,000 ohms 

R30— 4700 ohms 

R34— 27 ohms 

R37— 10 megohms 

R47— 500,000 ohms, multiturn potenti- 
ometer, PC -mount 

R48 — 300 ohms, potentiometer, panel- 
mount with switch (commonly used in 
TV receivers) 

Capacitors 

C1, C3, C4, C6, C14, C28— 0.47 u.F. 35 

volts, tantalum 
C2— 10 jiF, 35 volts, electrolytic 
C5 — 0.1 u.F, ceramic disc 
C7, C9, C11-C13, C18, C19, C22-C24, 

C26, C27— - 0.01 ^F, ceramic disc 
C8, C17— 4.7 uF, 35 volts, electrolytic 
C10 — 3.3 m-F, 35 volts, tantalum 
C15— 68 pF, ceramic disc 
C16 — .005 ^F, ceramic disc 
C20 — 47 pF, ceramic disc 
C21 — 8 pF, ceramic disc 
C25— 2200 (iF, 1 6 volts, electrolytic 

Semiconductors 
IC1 — 741 op-amp 
IC2— 555 timer 

IC3 — 4093 quad 2-input nand Schmitt trig- 
ger 
IC4 — 4020 14-stage binary ripple counter 



2 (or multiples of two), the output pulse 
will be unevenly spaced and of uneven 
width. Fortunately for the Heart-a-Matic, 
however, that is unimportant because we 
are only interested in the number of pulses 
and not in a particularly smooth wave- 
form. Rate- multipliers IC9 and ICI0 are 
cascaded so they can handle division by 
an eight-bit number. 

Half of IC8 , a 556 dual ti rner, is used as 
an astable multivibrator, or frequency 
generator. With the component values in- 
dicated, the free-running frequency is 
about 400 kHz. although the actual figure 
is not critical. That's because the signal is 
fed to the cascaded 4089's and all we're 
interested in is the ratio of their base rate 
to their multiplied rate. The multiplied 
rate is output at pin 6 of IC9 and routed to 
the clock input of IC4, a 4020 binary 
ripple-counter. The base rate, output at 
pin 1 of IC9, is sent to IC6, a 4553 three- 
digit binary counter. The outputs of the 
4020 that are decoded all go high when 
the counter reaches a number you should 
remember from earlier— 7200. With all 
that behind us, we can now explain the 
device's operation much more simply. 



LIST 

IC5 — 4012 dual 4-input nand gate 

1C6— -4553 3-digit binary counter 

1C7— 4543 BCD-to-7-segment latch/ 
decoder/driver 

IC8— 556 dual timer 

IC9, IC10 — 4089 binary rate multiplier 

IC1 1—7805 5-volt regulator 

IC12-IC1 5—4508 dual 3-state 4-bit latch 

IC16-IC19 — 4040 12-stage binary ripple 
counter 

IC20 — 4001 quad 2-input nor gate 

IC21 — 4017 decade counter 

IC22 — 4049 hex inverter 

IC23— 5369 60-Hz timebase 

IC24— FPA104 infra-red emitter/sensor 
array 

Q1— 2N3391 

Q2— 2N3904 

Q3— 2N2222 

Q4-Q6— 2N3906 

SCR1— ECG 5400 

LED1-LED3— FND500 0.5-inch com- 
mon-cathode 7-segment display 

D1, D2— 1N914or 1N4148 

D3— 1 N4001 

XT AL1— 3.579545 MHz color-burst refer- 
ence crystal 

SPKR — 8 ohms, 2-inch diameter 

S1— SPST switch {part of R48) 

J1 — 1 2-contact edge 
connector 

J2. J36-contact edge 
connector 

J4 — subminiature N.C., chassis-mount 

B1-B8—1. 5-volt "AA'celi 

Miscellaneous: PC boards, two ' AA" 
side-by-side battery holders, Velcro 
strip, plastic for cases, wire, shielded 
cable, solder, etc. 

The following are available from Hal- 
Tronix, P.O. Box 1101, Southgate, Ml 
48195: Set of six etched and drilled PC 
boards, $29.95; Board 1 (double-sided), 
$19.95. Add $2.00 for shipping & hand- 
ling; Ml residents add 4% tax. 



The controlling key is the interlock sec- 
tion of IC3 and IC5, and the heart of the 
device is the 4089' s. When the output of 
the IC3 latch goes high following a de- 
tected heartbeat, one of the octal-latch 
4508 's puts a number on the data bus. At 
the same time, two other things happen. 
A high is applied to pin 4 of the 400-kHz 
frequency generator, setting it in opera- 
tion, and a low is applied to the reset pin 
of IC4, the 4020 counter, enabling it. The 
rate multipliers begin outputting pulses to 
the 4020 at the rate of Vtt, the 556' s fre- 
quency multiplied by the number on the 
data bus, and sending the base-rate fre- 
quency to IC6, the three-digit counter. 
When the count at the 4020 reaches 7200, 
the output of IC5-b, a four-input nand 
gate, goes low and transfers the count 
present at IC6 into its internal latch. 

The same signal also travels to the re- 
set pin, pin 1 3 , of IC6 via C 1 2 and clears 
the counter to zero in preparation for the 
next count. The output of IC5-b is in- 
verted by IC5-a and returns to the latch 
formed by IC3-a and IC3-b, causing its 
output to go low. That disables the 400- 
kHz frequency generator, causes the 
4020, via inverter IC3-d, to reset to zero 
and hold there for the next heart-rate 
calculation, and returns the clock input of 
the 4017 decade counter to a low state 
until the next heartbeat. 

The sequence of events resembles 
those of the classic "do-nothing box." 
The Heart-a-Matic gets turned on, does 
its thing, and then turns itself off. In this 
case, however, the device performs a 
complex series of operations and then 
waits for the next incoming signal to 
retrigger it. 

The other half of IC8 is also configured 
as a frequency generator and is frequen- 
cy-modulated by the output of the 400- 
kHz generator. The result is a tone of 
about 1 kHz, that lasts as long as the other 
oscillator is running. That tone is fed to 
the speaker via volume-control R48 . An 
unusual side-effect of that is thai the dura- 
tion of the beep changes with the heart 
rate. The reason is that the lower the heart 
rate, the less time it takes to do the in- 
ternal arithmetic and the less time the 
400-kHz oscillator operates and enables 
the beep generator. The beep generator 
also supplies power to the decimal points 
of the displays for a visual as well as 
audible indication of the heartbeat. 

The counter section, IC6 and IC7, is 
fairly straightforward. The latter is a de- 
coder that feeds the three multiplexed 
common-cathode displays. The actual 
multiplexing is done by an internal oscil- 
lator in IC6 whose frequency is de- 
termined by the capacitor connected be- 
tween pins 3 and 4. Resistor R15 holds 
the reset pin of IC6 low until it receives a 
positive reset-pulse from IC5-b via CI 2. 

Inverter IC22-e is present because of a 
basic law of mathematics that says that 

continued on page 109 



46 



fMU^^ 







Part 2 



THE HIRST PART OF THIS 

article discussed the 
theory of operation of a good portion of 
the main board of the Picture Phone. 
We'll now complete that discussion; it 
will be helpful if you have Part 1 handy. 

Fast-scan counters 

The fast -scan counters are IC6. IC8, 
IC23 and IC39. Each IC is a four-stage 
binary counter that is cleared to all zeroes 
when pin 1 is taken to 
a logic-low state. 
When pin 9 is low, the 
counter stages are pre- 
set to the value hard- 
wired at pins 3-6. Pin 
2 receives the clock 
pulses, and responds 
to their positive-going 
edges. Both clear and 
load operations are 
synchronous — that is, 
they take place only 
on the positive-going 
edge of the clock 
pulse. When the load 
or clear pin is taken 
low, the counter stops 
and retains its value. 
If a clock pulse occurs 
while the appropriate 
pin is low, the counter 
will load or clear. 

The fast-scan dot 
counters are IC6 and 
IC8 (dots are the pix- 
els along a line of 
video). The dot coun- 
ter is analogous to the 
horizontal sweep in 
the camera and dis- 
play. The dot counters 
have two modes, one 
for the camera and one 
for all other op- 
erations. 

Let's consider non-camera operation 
first. The crystal oscillator supplies clock 
pulses to pin 2 of the dot counters. Note 
that pin 1 5 of IC6 is connected to pin 1 of 
IC8. That is the "carry" from the first IC 
to the second, and provides synchronous 
operation of both IC's. 

Figure 5 shows the timing of the dot 
counters, The counter clear pulse is pro- 
vided by IC10 at a count of 215. That 
means that the counter advances to 2 1 5 , is 
reset to zero, and begins to count again. 
The internal horizontal-sync pulse (IFH) 
is produced by counter inputs applied to 
IC42. The clock frequency, divided by 
216 (the count from zero to 215), gener- 
ates the correct horizontal-sync fre- 
quency. 

Signal "J," which is low between the 
counts of zero and 127, serves several 
purposes. It is delayed by one clock pulse 



to form IFHB, the internal fast-scan 
blanking signal, which blanks the display 
in all modes. That signal is also applied to 
IC28 to control when data can be written 
to memory. Memory- write takes place, 
and the display is unblanked, when the 
counter is between zero and 127, 

Now let's look at the operation of the 
dot counter in the "snatch" and camera- 
display modes. The clocking signal is de- 
rived from the synchronous oscillator; 




Before you build your Picture Phone, you should know how 
the device works. We 'II conclude our discussion of that topic in 
this pan 1 . 



JOSEF BERNARD, 

TECHNICAL EDITOR 



and IC10, which supplies the clear 
pulse, is disabled. The counter advances 
until a horizontal -sync pulse from the 
camera (EFH) takes the load pin low. 
The counter is preset to a value of 217, as 
determined by the fixed inputs to pins 3-6 
of IC6 and IC8. The counter resumes 
counting at a preset value of 217 when 
EFH is no longer present. When it reaches 
its maximum count of 255, it resets to 
zero and starts counting again. The time 
spent counting from 2 1 7 to 255 represents 
blanking of the left-hand edge of the pic- 
ture; the time between 128 and EFH is 
used for right-hand blanking. 

The load pin is controlled by an RS 
flip-flop made from IC15-C and IC15-d. 
That flip-flop insures that the load pin 
remains low until a clock pulse to load the 
counter has arrived. 

The EFH signal is applied to the clear 
pin of IC32 to insure that the clock always 



starts with the same polarity. 

The fast-scan line counters are IC23 
and IC39. Let's first look at how they 
work during the non-camera mode. Dot- 
counter signal ' 'J' ' is used as the clock 
pulse, making the line counter advance 
one step for each line. Nine count-stages 
are needed; the extra stage is supplied by 
IC32 and is the least significant bit. 

Figure 6 shows that the counter adv- 
ances to a count of 262, is cleared, and 
starts again at zero. 
The clear pulse is sup- 
plied by IC47, which 
is hard-wired with the 
eight most-significant 
bits of the line coun- 
ter. The clear pin is 
held inactive when the 
camera is in use by 
connecting it to the 
logic- 1 present at pin 
10 of rC48. 

The internal fast- 
scan vertical sync 
(IFV) comes from 
IC31. 

When the camera 
display is viewed, the 
clear function is dis- 
abled and the line 
counter is preset 
whenever a vertical - 
sync pulse occurs. 
When the counter is 
preset and the sync 
pulse from the camera 
is completed, the 
counter starts count- 
ing. When the count 
reaches 511, the next 
count, zero, allows 
display and writing to 
memory to begin. The 
time that is spent in 
counting from the pre- 
set value to zero is used to allow the 
camera's blanking-function to be com- 
pleted. 

The line counter advances two counts 
for each slow-scan line to allow each line 
to be displayed twice for an easier-to- 
view picture. There are 128 slow-scan 
lines, which means that 256 lines-per- 
field (or 512 lines-per-frame) will be dis- 
played. Since NTSC standards call for 
525 lines per frame, a small portion of the 
picture at the top and bottom is blanked. 

Slow-scan clocks 

There are two slow-scan clocks. One is 
derived from the master crystal oscillator 
and is used for all functions except slow- 
scan reception. The second clock is free- 
running, and is synchronized to the slow- 
scan horizontal-sync pulses. The clocks 
are selected by IC13, a 4PDT multi- 
plexer. 



CO 



CO 

m 

ID 

ID 
03 
M 

49 



PARTS LIST 



All resistors Vi-watt, 5% unless otherwise 
noted 

R1-R3, R43, R78, R139, R202— 22,000 
ohms 

R4, R201— 10 megohms 

R5, R6, R8, R9 T R50, RBO— 15,000 ohms 

R7— 620 ohms 

R10, R12, R15, R54, R93-R95, R102, R110, 
R209, R211, R714-R716 — 4700 ohms 

R1 1 , R13, R14, R16-R18, R86. R99— 10.000 
ohms, 1% 

R19, R20, R27, R 147— 39,000 ohms 

R21— 20,000 ohms 

R22, R23— 18,000 ohms 

R24— 8200 ohms 

R25, R26, R145, R1 46— 82,000 ohms 

R28, R42, R51, R136, R140, R142, R204, 
R205, R710, R71 1—10,000 ohms 

R29 — 470,000 ohms 

R30, R47-R49, R53— 2200 ohms 

R31, R79, R1 48— 100,000 ohms 

R32, R108— 2700 ohms 

R33— 150,000 ohms 

R34, R40, R52, R96, R109, R137, R144, 
R704, R717— 1000 ohms 

R35-R39 — not used 

R41 — 680,000 ohms 

R44 — 47,000 Ohms 

R46— 33,000 ohms 

R55, R76. R112, R707— 100 ohms 

R56— 100 ohms, trimmer potentiometer 

R57— 3300 ohms 

R58, R77, R111— 330 ohms 

R59, R703, R712, R71 3-^*70 ohms 

R60— 1 00 ohms, 1 % 

R61-R75— 26,1 ohms, 1% 

R81-R84— not used 

R85, R98— 20,000 ohms, 1% 

R87, R100— 4990 ohms, 1% 

R88, R1 01— 2490 ohms, 1% 

R89-R91— not used 

R92, R200— 680 ohms 

R97— 47 Ohms 

R103— 820 ohms 

R1 04 — 2000 ohms, trimmer potentiometer 

R105— 1200 ohms 

R106. R107, R138, R141, R143, R203— 
1 000 ohms, trimmer potentiometer 

F113-R116, R125-R135— 33 ohms 

R117-R123— not used 

R144 — 68,000 ohms 

R149-R199— not used 

R206, R207— 220 ohms 

R210— 560 ohms 

R212, R213— 33.2 ohms, 1% 

R314, R315, R317, R318— 0.33 ohms, 2 
watts 

R316— 220 ohms, 2 watts 

R601— 130 ohms, 2 watts 

R701 — 100O ohms, panel-mount potentio- 
meter 

R702 — 1 0,000 ohms, panel-mount potentio- 
meter 

R706 — 1 megohm 

R708, R709— 1800 ohms, 1 watt 

co Al I ea pac itors My lar or m ica u n I es s ot h er- 

y wise specified 

§ C1-C6— ,022,uF 

dc C7, C24, C25, C38, C200, C240-C243— .01 

o [if ceramic disc 

y C8, C10, C12, C17— .0047 piF 

w C9— .0068 nF 

Q C11.C207— ,018mF 

§ C13, C15, C18, C19, C23, C263-C266— 22 

rx /iF, tantalum 

50 



C14— 10 pF, tantalum 

C16, C22, C206, C703— .001 fiF, monolithic 

or ceramic disc 
C20, C201— 27 pF, monolithic or ceramic 

disc 
C21.C28-C31— 470 pF 
C26— not used 

C27 — 33 pF, monolithic or ceramic disc 
C32, C220-C227--0.1 ^F, ceramic disc 
C33, C41, C208, C31 7-C320— 2.2 fiF, tan- 
talum 
C34, C230-C237, C250-C262. C702— 0.1 

ju.F, ceramic disc 
C35. C202-C205— 100 pF 
C37, C39— not used 
C40— .047 fiF 

C309— 500 iif, 1 2 volts, electrolytic 
C31 0—9200 fiF, 15 volts, electrolytic 
C31 1—450 fiF, 25 volts, electrolytic 
C312— 5800 ^F, 25 volts, electrolytic 
C601 — 500 fiF, 25 volts, electrolytic 
C701— 2 tif. tantalum 
Semiconductors 
IC1-IC4, IC17-IC20, IC33-IC36, IC49-IC52— 

^PD41 1 (MM5280) 4K x 1 dynamic RAM 
IC5, IC13, IC21, IC37, IC46, IC48, IC55— 

74LS1 57 quad 2-1 multiplexer 
IC6, IC8, IC9, IC23, IC24, IC39-IC41— 

74LS163 presettable binary counter W/ 

IC7. IC26, IC57, IC58, IC61— 75LS04 hex 
inverter 

IC10, IC31 , IC47— 74LS30 8-input nano gate 

IC11. IC32— 74LS107 dual JK negative- 
edge-trigger flip-flop 

IC1 2—4046 CMOS phase-locked loop 

IC14, 1C15, IC45— 74LS0O quad 2-input 
nano gate 

IC16, IC29. IC65— 74LS74 dual D flip-flop 

IC22, IC38, IC71, IC72— 74LS153 dual 4- 
input multiplexer 

IC25, IC42, IC88— 74LS20 dual 4-input nano 
gate 

IC27, IC67, IC68— 74LS10 triple 3-unit nand 
gate 

IC28, IC43, IC66— 74LS25 dual 4-input nor 
gate 

IC30— 74LS221 dual one-shot 

IC44, IC62— 74LS32 quad 2-input positive 
or gate 

IC54, IC56— 74LS175 quad D flip-flop 

IC59— 74LS08 quad 2-input and gate 

IC60, IC63, tC64— 74l_Sl3dual Schmitt trig- 
ger 

IC66— 3245 quad TTL-to-NMOS memory 
driver 

IC69, IC70— 74LS02 quad 2-input nor gate 

IC73-IC80— LM71 1 dual difference- 
comparator 

IC81-IC84— not used 

IC85, IC86— 74LS86 quad exclusive-or gate 

IC87 — 4066 CMOS quad bilateral switch 

IC89— 566 function generator 

IC90-1C94, tC105— 1458 dual 741 op-amp 

IC95-1C104— not used 

Q1, Q2, Q4, Q5, Q8-Q13— 2N4124 or equiv- 
alent 

Q3, Q6— not used 

Q7— 2N4126 or equivalent 

LED1-LED3— jumbo red LED 

D1-D11, D13-D1S, D27-D33— 1N914 or 
1N4148 

D1 2— not used 

D19-D26, D601, D602— 1N4007 

DT601 — gas discharge tube (Joslyn Electro- 
nics type 2022-44 or equivalent) 



CB1— 0.6-amp circuit breaker 

T1 — dual-secondary type: 1st secondary: 

25VCT, 1 amp; 2nd secondary: 12.6VCT, 

1 .5 amps (see text and below) 
T601 — phone-line matching transformer 

(Microtran type 61 12 or equivalent) 
S1 — 4P5T rotary switch 
S2-S4 — N.O. momentary pushbutton switch 

S5— SPDT toggle switch 

S6— SPST toggle switch 

J1 -J2— not used 

J3 — 36/72-pin PC-board edge connector 
(36 contacts for each side of board, two 
contacts per pin) 
J4 — socket for mod u I ar telephone con n ecto r, 

panel-mount 
J5— DB25-S 25-pin female "date-type" sock- 
et, panel-mount 
J 6, J7— RCA-type phone jack, panel-mount 
J8, J9— female coaxial connector, panel- 
mount (BNC- or SO230-type) 
TB601— miniature 8-terminal barrier strip, 

PC- mount 
RY601, RY602— 4P2T 12-volts, PC-mount 

(Potter & Brumfield T1 0-E2-Z4-1 2VDC or 

equivalent) 

Miscellaneous: PC boards, perforated con- 
struction board, IC sockets, RQ59 cable, 
shielded audio cable, 4-conductor telephone 
cable w/modular plug, 3-conductor line cord 
w/plug, enclosure, hardware, etc. 

The following are available from Robot 
Research Inc., 7591 Convoy Court, San 
Diego, CA 92111, (714) 279-9430: Assem- 
bled & tested Model 535 Picture Phone, 
FCC registered for direct connection to 
telephone line (KIT-1) (14 lbs.), $1195.00; 
assembled and tested No. 400929C main 
PC board (KIT-2) (4 lbs.), $495.00; assem- 
bled and tested Picture Phone chassis. 
Including telephone adaptor board, but 
less main board, (KIT-3) (1 2 lbs.), $695.00: 
kit of No. 400929C main PC board with all 
main-board parts (KIT-4) (5 lbs.), S295.00; 
kit Including chassis and chassis parts, 
and telephone adaptor board and parts, 
but less main board, (KIT-5) (12 lbs.), 
$445.00; telephone adaptor board kit in- 
cluding board and parts (KIT-6) (3 lbs.), 
$79.50; etched, drilled, and plated- 
through main board (KIT-7) (3 lbs.), 
S5S.00; etched, drilled, and plated- 
through telephone adaptor board (KIT-8) 
(2 lbs.), $19.95; T1 (KIT-9) (4 lbs.), $29.50; 
T601 (KIT-1 0) (2 lbs.), $24.50; OT1 (KIT-1 1 ) 
(1 lb.), $8.50; kit of 32 1% resistors for 
main board (KIT-1 2) (1 lb.), $12.00; in- 
dividual 1% resistor (KIT-1 3) (1 lb.), $0.35; 
Mode) 535 Picture Phone enclosure kit 
with mounting rails for main board and 
back plate for controls (KIT-1 4) (6 lbs.), 
$99.50; kit of front panel parts only, (KIT- 
15) (2 lbs,), $59.50; assembled & tested RF 
modulator, less power supply and enclo- 
sure (KIT-1 6) (1 lb.), $29.00; RF-modulator 
kit, less power supply and enclosure (KIT- 
17)(1 lb.), $19.50. For Information on other 
parts, write to Robot Research. 

CA residents please add 6% sales tax. 
All prices F.O.B. San Diego — check with 
UPS for shipping charges; please add 
$0.50 per $100.00 of value above first 
$100.00 for insurance. MC and Visa 
accepted. 



127 



160 176 



715 



CLEAR 



127 



TIMING WITH RESPECT TO "J" IS 
A FUNCTION OF CAMERA LINE 
FREQUENCY 



717 



LOAD 



FIG. 5— FAST-SCAN dot counter has two modes — a is used for memory display, b for frame grabbing 
and camera display. 




7.55 



H h 



^ ^ 



252 255 



262 



CLEARi- 




255 



-*v 



-**- 



603 



LOAD 



HV 



-iV 



F1G. 6 — FAST-SCAN line counter timing for memory display (a), and camera display (b). 



The crystal-derived clock pulses begin 
with the 60-Hz ' 'U' ' output of the fast- 
scan counter. It is divided by four by 
IC1 1. The resulting 15-Hz pulse train is 
applied to one input of PLL (Phase- 
Locked Loop) IC12. The other input to 
that IC is the clock oscillator's output 
divided by 139, making the output of the 
PLL 15 X 139, or 2085 Hz. That be- 
comes the slow-scan clock. It allows for 
1 28 pixels and 1 1 sync counts per slow- 
scan line. 

The synchronized clock pulses are 



generated by IC60. Its free -running fre- 
quency is controlled by R143. As the 
frequency is increased, the counter takes 
less time to address i 28 memory ' 'cells' ' 
and a shorter line is displayed. The clock 
is synchronized with the incoming signal 
by having the incoming slow-scan sync 
pulses cause the oscillator to stop and 
restart in phase with them. 

The slow-scan clock is aligned with the 
fast-scan system by retiming the leading 
and training edges of the clock pulses 
with a section of IC16. A control signal, 



CAUTION: 

FCC regulations prohibit the con- 
nection of this device to telephone 
lines without the use of an approved 
coupling device. The only exception 
to this is the assembled and tested 
unit available from the suppliers in- 
dicated in the Parts List. A coupler 
that meets FCC requirements will 
be described in the next part of this 
article. Do not attempt to connect 
the Picture Phone you build without 
it — it's illegal to do so. 

"Z," controls all the slow-scan func- 
tions. It is in operation only for the dura- 
tion of the slow-scan memory-write cy- 
cle. Its use for retiming the slow -scan 
insures that the clock will not change dur- 
ing a slow-scan read or write memory 
access. 

Slow-scan counters 

The slow-scan counter is made up of 
IC9, IC24, IC40 and IC41 . They function 
the same way as their counterparts in the 
fast-scan circuit. 

The slow-scan dot counter uses IC9 
and IC24. It has two modes of op- 
eration — one to write slow scan to mem- 
ory, and one to read it. Let's look at the 
read-mode first. The clock signal is de- 
rived from the crystal oscillator. The 
clear signal is derived from IC25; the 
load function is inactive. The counter is 
cleared at a count of 1 39 to provide 1 28 
memory "cells" per line and 1 1 sync 
counts. 

When slow scan information is to be 
written to memory, the free-running 
clock is used. The clear signal is derived 
from a flip-flop formed from IC 14-a and 
IC14-b. The flip-flop is set by an incom- 
ing sync pulse, and reset by a clock pulse. 
That is done to make sure that a clock 
pulse to clear the counter occurs while the 
clear pin is low. The slow-scan sync 
pulse is allowed to reset the counter only 
after 128 counts (the end of a line) to 
insure noise immunity. In other words, 
false pulses can't interrupt a line as it is 
being written. 

The line counter uses IC40 and IC4I . A 
clock pulse occurs when each slow-scan 
line has been completed. The counter is 
reset to zero in the "read" mode at a 
count of 127 by the "U" signal. In the 
"write " mode it is cleared by the external 
vertical-sync signal applied to an RS flip- 
flop made from IC14-C and IC14-d. The 
flip-flop is reset by IC43 and IC45-a. 

When a picture is grabbed from the 
camera, the line counter is set to all ones, 
and on the next clock pulse to all zeroes. 
That one-line time generates a slow-scan 
vertical-sync pulse. 

Address selector 

The memory address-lines are driven 
by the fast-scan counter to generate a 
video signal for fast-scan display, and 
also by the slow-scan counter to generate 
a slow-scan signal. The memory address- 



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COLUMN 3J L 



COLUMN 1 L 



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COMPLETED MAIN BOARD of the Picture Phone plugs Into 36/72-pirt edge connector mounted at front 
of enclosure. 



lines are connected to the appropriate 
counter by an address multiplexer made 
up of IC5. IC2I and [C37— 4PDT switch- 
es, each of which switches four address 
lines. Resistors on the leads to the mem- 
ory IC's damp reflections so that the ad- 
dress voltages will not ring. 

The address lines are in the "slow 
scan" mode during time "Z," which 
takes place for 16 dots following the 
right-hand edge of the fast-scan picture. 
In other words, slow-scan memory access 
takes place just after fast-scan access for 
the current line is completed. When "Z" 
becomes active, the address multiplexer 
switches to slow scan, and the slow-scan 
counter is inhibited from changing state. 
The "Z" signal is generated by IC25-b. 

Fast-scan memory multiplex 

To obtain the speed required for fast- 
scan operation, memory operation is mul- 
tiplexed. The multiplexing is done with 
the memory ti. (Chip triable) pulse. Fig- 
ure 7 shows the ce pattern. Note that 
successive memory columns are over- 
lapped by 50%. 

The cf. signal is formed by a delay 
flip-flop, IC65, that uses "B" as data and 
"A" (delayed) as a clock signal. Signal 
"A" is delayed by an RC circuit that 
feeds Schmitt trigger IC60. The delay is 
provided to insure that memory address- 
lines are stable before ce goes high. 

The ce signal is a zero-to— + 12-volt 
pulse translated from 5-volts by IC66. 

Slow-scan memory multiplex 

Memory multiplexing is performed by 
the two lowest-order bits on the memory 
address-lines. In other words, each bit of 



FIG. 7— EACH COLUMN of memory overlaps the 
next by 50%. See text for details. 

the 4-bit pixel nybble requires four mem- 
ory IC's, arranged in four columns. The 
two lowest-order address bits determine 
which column is to be addressed. Mem- 
ory-speed increase is achieved by over- 
lapping the column- select address. 

Slow-scan memory addressing must 
also be able to select the desired memory 
column as part of the complete address. 
The two lowest -order bits from the slow- 
scan counter, "a" and "b," are com- 
bined into column-select pulses by IC69. 

Each of the 16 memory IC's has a cs 
(Chip Select) pin that is used for slow- 
scan memory column selections. The cs 




REAR PANEL of Picture Phone, Circuit-breaker 
reset is located above line cord at left. 



pulses come from IC69 and are passed on 
by IC70 during the slow-scan access 
time. That IC holds all IC's selected at all 
other times. 

In addition to addressing the memory 
for slow scan, it is necessary to time the 
storage of the incoming slow-scan in- 
formation. The required timing signal is 
generated by IC7I, a DP4T switch of 
which only one pole is used. The inputs of 
IC71 consist of the slow-scan cs pulses 
generated by IC69. 

The signals used to control IC71 are 
"X" and "Y," the fast-scan cs pulses. 
Therefore, when the slow- and fast-scan 
cs pulses coincide, a "read store" pulse 
will be generated. In other words, when 
IC69 has selected column one, and "X" 
and "Y" have also selected column one, 
then — and only then — will a "read 
store" pulse be generated. 

Multiplexer IC7 1 is enabled by a con- 
trol signal called SSME (Slow-Scan 
Memeory Enable), which is active for 
exactly four consecutive fast-scan ad- 
dresses. That means that SSME is active 
just long enough to sample each memory 
column once. The SSME signal is gener- 
ated by IC27-b. It is a small portion of 
"Z," which is the time for slow-scan 
address to be applied to the memory. 
Since SSME takes place later than "Z," 
any transients created by the address 
switchover from fast- to siow-scan die out 
before a read sample is taken. 

Write control 

The we (Write Enable) signal to the 
memory IC's must also be multiplexed so 
that the write and ce inputs to an IC will 
coincide. 

Write-control signals are formed by 
IC67 and IC68-b. Those signals are active 
one column at a time in response to the 
values of "A" and "B," the lowest- 
order bits of the fast-scan counter. 

A common control-line to the we en- 
coder determines when writing is to take 
place. That control line has two sourscs, 
one for fast scan and one for slow scan. 

The control signals, generated by 
IC28, are combined by lC44-b. 

Snatch control 

When the snatch button is pressed, a 
one-shot puts out a pulse that lasts for 
several fast- scan fields. The pulse is re- 
timed by a section of delay flip-flop IC29 
so that the useful snatch command starts 
and ends at the bottom of a TV picture. 
That prevents any errors that might result 
from the snatch pulse ending in the mid- 
dle of a picture. Another section of 1C29 
retimes display selection so that the 
changeover between display memory and 
the camera takes place when the picture is 
blanked. 

In the next part of this article we'll 
discuss the telephone interface and pow- 
er-supply circuits. We will also begin to 
look at the construction and alignment of 
the device. R-E 



52 



'•* / 



*<S#. 




Often, the hardest task in building a project is obtaining 
the various parts that you need. Keeping a well-stocked 
junk box can save you a considerable amount of time, 
effort, and money! 

KARL T. THURBER, JR., W8FX 

ONE OFTHE MOST REWARDING WAYS TO GAIN EXPERIENCE IN ELECTRONICS IS 

to build electronics projects. Besides the satisfaction of accomplishment, 
you learn a great deal in the process involved. 

Today, it isn't an easy matter to obtain the right parts, at the right time, 
and at the right price. The search for and selection of electronic com- 
ponents for projects can be a very disheartening job, particularly when 
it's seemingly impossible to obtain certain parts, or the price you must 
pay for them is excessive. You can get the parts you need, when you need 
them, and at a reasonable price, if you are willing to take an organized 
approach to parts procurement and do a good deal of preparatory spade 
work before picking up soldering iron and pliers. 

In this article, we will examine the need to get organized for the task; 
look at parts-selection criteria and the question of substitutions; review 
various sources of parts; and discuss details of component identification 
and testing. 

As you'll see, once you have a clear view of the process, shopping tor 
parts is no longer the formidable challenge it might otherwise be. 

Catalogs and reference material 

Before buy in a parts, it pays to be organized— to have done some pre- 
planning before you start looking for specific parts for a given project. 
Some of the things you can do in advance include laying in a good store of 
catalogs, reference sheets, and reference books; buying-in-advance "sta- 
ple" and bargain-priced parts; and setting up a well-stocked junk box. 
It surely pays to accumulate a broad range of catalogs. No builder's 
library is complete without them. With a little effort, you will find that 
virtually any desired part, or a usable substitute, will be listed in .some- 
one's catalog or cross-reference. You may also find that a single firm may 





have all, or almost all, of the parts re- 
quired for a given project, eliminating the 
need for repeated shopping forays or in- 
efficient orders to a number of mail-order 
firms. Having a number of catalogs at 
hand also allows ready price comparisons 
between firms. 

Having a good reference file, or recent 
issues of major electronics publications 
such as Radio-Electronics; amateur 
magazines such as CQ, Ham Radio, and 
QST; and a variety of computer-oriented 
magazines. Byte, Microcomputing, and 
Popular Computing will provide a good 
background. The magazines also list the 
addresses of the major suppliers, along 
with their ordering policies. Of course, 
single-page magazine ads can't include a 
supplier's full stock, and are no substitute 
for the catalogs themselves. 

Another reason for obtaining the larger 
catalogs is that those serve as excellent 
reference files for various components, 
and often provide good sources of cross- 
reference data, particularly for solid-state 
components. Note that many of the dis- 
tributors offer two or more catalogs, such 
as a consumer-type catalog oriented to 
hi-fi or CB, and an industrial catalog that 
would normally be more suitable. 

In addition, you should acquire the fac- 
tory service manual, schematic diagram, 
and component parts list for any item of 
electronics gear you buy. A surprising 
quantity of semi-professional and pro- 
fessional-electronics equipment is sold 
today with no more than a user's manual, 
which is of little help in servicing and 
parts replacement. Obtaining the proper 
manuals and parts lists while equipment is 
currently being manufactured is much 
easier than trying to obtain such materials 
later on, when needed information may 
no longer be readily available. 

To facilitate original construction, it's 
worthwhile to have on hand a selection of 
standard reference books and manuals, as 
well. The publications required, of 
course, will depend upon the particular 
type of project work undertaken. Some of 
the more important, all-round useful 
reference texts include the Editors and 
Engineers' Radio Handbook, the Master 
Tube Substitution Handbook, Transistor 
Substitution Handbook, TTL Data Book, 
Transistor Specifications Manual, and 
Reference Data for Radio Engineers; the 
ARRL Electronics Data Book and Radio 
Amateur' s Handbook, and several others. 
A handy cross-reference manual is the 
Archer Semiconductor Reference Hand- 
book, a useful guide to Radio Shack's 
semiconductors that's also a substitution 
to and cross-reference guide for more than 
y 100,000 solid state devices. Another 
O Radio Shack reference is Forrest Mims' 
£E Engineers Notebook, which contains 
fjj tried-and-tested applications for most 
Oj popular linear and digital IC's. Other 
o helpful parts information sources are 

< Photos courtesy of Radio Shack and GC Electro- 
rx nics. 



Motorola's Semiconductor Cross- 
Reference Guide and Discrete Hybrid 
Components Handbook. Sylvania's ECG 
Semiconductor Replacement Guide; and 
RCA's SK Replacement Guide. 

Buying in advance of needs 

Is stocking parts in advance of specific 
project needs a good idea? It's true that 
with a few judicious purchases, you can 
stockpile many of the components needed 
for future projects. On the other hand, an 
apparent bargain isn't one, unless there's 
a real prospect of the part or parts ul- 
timately being used. 




BUYING LARGE ASSORTMENTS Of com- 
ponents and hardware can result in savings, but 
only if the parts are likely to be used. 

Mail-order dealers offer all kinds of 
special deals — hardware assortments, re- 
sistors, knobs, transistors, IC's, 
potentiometers, transformers, diodes, 
capacitors, and various surplus com- 
ponents and assemblies. Many of those 
offerings are indeed bargains, if carefully 
surveyed and even more carefully pur- 
chased. It's generally worthwhile to take 
advantage of quantity offerings and spe- 
cialized assortments , tempering one ' s en- 
thusiasm for a "good deal" with a realis- 
tic expectation of when, and if. the con- 
templated bulk purchase will likely be put 
to use. A small investment in component 
assortments usually represents money 
well spent; however, there is usually little 
that can be done about a poor choice — 
you take what you get and hope to be able 
to use most of it. 

For initial stock-up, some useful com- 
ponents include poly-bag assortments of 
disc ceramic, mica, and small electrolytic 
capacitors; low-wattage resistors; diodes, 
and hardware. On the other hand, assort- 
ments of precision resistors, large 
electrolytic capacitors, IC's, and transis- 
tors arc probably too specialized and may 
not represent good value. The key to 
selecting true bargains lies in choosing 
components that you are most likely to 
use in your projects. 

There are some cautions to keep in 



mind. Buying in advance of your needs is 
intended to build an inventory of common 
parts, not to produce specific parts for an 
intended project. It's unusual to find just 
what you need for a particular project 
from a grab-bag assortment. Whenever 
you need a specific part, order that part. 

Carefully note the makeup of parts 
assortments. Are the parts offered all of 
one (possibly oddball) value, or are they 
of different values? What are the toler- 
ances and power ratings? Are the leads 
full-length or too-short PC -board length? 
Are the components new, used, or sur- 
plus; tested or untested; Firsts or seconds; 
marked or unmarked; old or fresh; usable 
or dubious? 

All of those considerations play an im- 
portant part in determining whether buy- 
ing in advance of needs is a worthwhile 
approach or a waste of money. 

Acquiring a junk box 

Most builders have a junk box that can 
be a handy and money-saving device for 
both construction projects and repair 
jobs. Not only does the well stocked junk 
box satisfy convenience and economic 
needs, but it can also provide a valuable 
educational experience in component 
identification and substitution practices 
for the beginner. 

Assembling a useful junk box is a 
prime objective of most electronics hob- 
byists. The accumulation gives you the 
parts you need for projects, when you 
need them, at reasonable prices — 
sometimes even at no cost. While you 
may have to spend some money to acquire 
a foundation, it's possible to accumulate a 
large assortment of components in- 
expensively, if you aggressively search 
for bargains. 




ELECTRONICS FLEA MARKETS often are a 
good place to acquire parts at a reasonable cost. 

The sources for junk box parts are 
myriad, and they include local purchases, 
surplus/salvage, mail order, flea markets, 
auctions, and other sources. Probably the 
best, lowest-cost way to build an initial 
parts inventory is to salvage usable com- 
ponents from junked electronics gear. 
Components such as switches, 
potentiometers, coils, diodes, transform- 
ers, resistors, and capacitors arc often 
salvaged from such equipment. In earlier 
days many of those components could be 
obtained from old radios, defective TV 



54 



sets, discarded amateur equipment, and 
government surplus gear — components 
large and small being saved with the ex- 
pectation that they could be used again in 
some future project. 

Those were the good old days, and by 
and large, junked gear — particularly that 
of the tube-type variety — provides a 
shrinking source of junk box parts. With 
the advent of solid-state equipment, 
printed circuits and specialized transis- 
tors, and IC's, it's harder to "recycle" 
those components into useful junk box 
parts than it was 15 or 20 years ago. The 
trend in junk box acquisition is toward 
judicious buying of discrete components 
in advance. We've already discussed 
parts-selection tips and cautions, and they 
apply equally to purchases for the junk 
box. 

Regardless of what methods arc used to 
procure for the junk box, the com- 
ponents — particularly the smaller, easily 
damaged ones — should be carefully 
segregated by type and value, and placed 
in labeled jars, plastic drawers, or even 
small boxes — whichever suits your par- 
ticular style. The key is that the storage 
procedures used should allow fast and 
positive recovery of the parts when 
needed. Components that can be tested 
should not be used without first checking 
their electrical condition, regardless of 
how good they may look physically. 
We'll delve into component identifica- 
tion and testing later; suffice it to say at 
this point that a multimeter and grid-dip 
oscillator are two very important testing 
devices for builders. 

A final point on junk boxes: After 
you've developed a respectable junk box, 
don't hesitate to use it for your projects or 
repairs. You will save money using "pre- 
owned" parts, and the risk of improper 
substitution of a part in a circuit is usually 
not too great (except to that particular 
part). Even if a substituted junk box part 
fails, a good deal of learning has taken 
place! 

Developing the parts lists 

Most published projects include an ite- 
mized parts list that identifies the various 
components' size, value, and nomencla- 
ture, as well as required voltage, current, 
and power- hand ling capability. Some 
parts lists even state brand names and 
recommend sources for hard-to-find and 
critical components. 

Even when a clear and definitive parts 
list is provided, you should carefully re- 
view the construction project, looking 
closely at the schematic diagram, photos, 
and explanations of special circuitry and 
parts requirements. In many cases, the 
author will point out critical components 
that should not be changed. Based on 
your judgment, other parts may be sub- 
stituted, possibly from existing junk box 
stocks. We'll talk more later on the ques- 
tion of parts substitution and how far one 
can deviate from specified values without 




CLEAR PLASTIC STORAGE BOXES can be extremely useful for quick, positive part identification. 



affecting performance. 

The author's parts list should trigger 
you to work up additional subsidiary parts 
lists. Those may logically take the form of 
lists showing which parts are best pro- 
cured from your junk box: which are best 
procured by mail-order; which are best 
acquired from surplus or salvage sources, 
and which can be purchased locally. After 
checking your junk box, look over the 
local purchase and surplus lists next, with 
unavailable items added to the mail-order 
list. In large, complicated projects, it may 
also be useful to have each list further 
divided by type of component for con- 
venience in searching for the required 
parts. 

From practical and economic stand- 
points, it's often wise — even necessary — 
to make appropriate component sub- 
stitutions. We'll turn to those next. 

Parts selection and substitution 

As the prices of individual components 
increase, it's important to "make do" 
with the parts you have on hand. It's 
possible to substitute components within 
limits, and yet have a device function as 
intended. Besides the financial advan- 
tages of using existing stocks, it's a real 
time saver to be able to use on-hand com- 
ponents rather than having to shop for 
new ones. Also, it's worthwhile to get a 
feel for the range and types of sub- 
stitutions that can be made so as to devel- 
op flexibility when shopping for com- 
ponents — since local suppliers and mail- 
order houses will not always have exact 
specified components in stock. 

Many inexperienced electronics enthu- 
siasts have an unnecessary fixation on 
obtaining the exact parts and values in- 
dicated in a construction piece, fearing 
that the finished equipment will not func- 
tion correctly if any liberties are taken 



with the stated parts list. Usually such 
fears are exaggerated. Unless a "mirror 
image" of the item is required, identical 
parts are not needed. In most cases, parts 
substitutions can be made, within reason- 
able bounds. Component specifications 
are not "graven in stone," as the saying 
goes. There is usually a tolerance range 
within which the hobbyist may work. 
Sometimes those are stated, though most- 
ly they are not. The trick to intelligent 
parts substitution, of course, lies in know- 
ing just what the boundaries of wise sub- 
stitution are. 

Obviously, if the construction article's 
author or circuit designer has highlighted 
critical components, you shouldn't 
change them. Special-purpose or close- 
tolerance IC's, transistors, tubes, capaci- 
tors, resistors, and other parts are best not 
substituted. But in many cases the com- 
ponent specified is what the designer had 
on hand, and represents an arbitrary 
specification. So, bearing in mind that 
most hobbyists are also experimenters, 
when you have trouble finding com- 
ponents with the exact specifications, try 
some substitutions of your own. using a 
combination of good judgment and close 
attention to available reference guides, 
catalogs, and substitution manuals. You 
may not have the experience to ascertain 
whether or not you'll be successful in 
making the substitution, but you'll never 
know unless you try! 

Most components, such as resistors, 
capacitors, inductors, transformers, and 
transistors, have ratings that are impor- 
tant. Those include power and maximum 
voltage and current ratings. The ratings of 
substituted components should be equal 
to or greater than those specified for the 
project. Generally speaking, over- rated 
components can be used in electronics 
projects. For example, a 1-watt resistor 



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can be substituted tor a '/:-watt resistor of 
the same value without concern, unless 
the larger physical size of the 1-watt unit 
causes a space problem. 

Active devices, such as transistors, are 
more difficult to substitute on a "rating" 
basis, due to the multiplicity of rating 
parameters involved. Still, similar guide- 
lines hold for those components, as long 
as the substitute has equivalent design 
parameters. One must be cautious in try- 
ing to substitute components with over- 
rated ones when the device is to perform a 
specific function at a particular value of 
current or voltage. In such a case, a 
"larger" unit would not be satisfactory. 
Zener diodes and other current- and 
voltage-regulating devices, for example, 
would fit into that category. 

Making a proper "ratings" substitu- 
tion is a great deal easier than making a 
"value" substitution. Each type of com- 
ponent is affected by different rules and 
guidelines, so it's worthwhile to look at 
each individually: 

I. Resistors. Fixed resistors are often 
easily substituted. Unless specified other- 
wise, fixed resistors commonly have a 
tolerance of ± 10 or 20% . Knowing that, 
you can usually safely substitute any re- 
sistor. If no tolerance is specified, work- 
ing in the ± 10% or 20% range is usually 
safe. One general exception is high- 
voltage power-supply bleeder resistors — 
those can be as much as 25% lower or 
50% higher than specified. 

In some applications, metal-film preci- 
sion resistors, manufactured to tolerances 
of ± 1 % or better, are required. That type 
of resi stor i s f requentl y s peci fted for h igh- 
stability/ultra-low -noise circuits in com- 
puters, voltage dividers, test equipment, 
and active filters. The stated tolerance 
must be maintained when substituting 
those types of resistors. 

Frequently, you can find resistors in 
your junk box that can be adapted for a 
substitution, using series and parallel 
combinations whose net resistance is 
close to the desired value. Resistors con- 
nected in series have the total resistance 
of the sum of the resistors — two 2000- 
ohm resistors in series have a total resis- 
tance of 4000 ohms. To find the effective 
resistance (R,) for resistors in series use 
the formula; 

R, = R1 + R2 + R3 + ... 

Two or more resistors can be connected 
in parallel to obtain the desired circuit 
resistance. When you do that, total resis- 
tance is always less than the lowest value 
used in the combination. Use the follow- 
ing simple formula to calculate the value 
of two resistors connected in parallel: 



R, = 



R1 x R2 
R1 + R2 



There are two major kinds of fixed 
resistors: composition or carbon, and 
wire- wound. Normally, do not use wire- 
wound resistors in circuits carrying RF 




APPROPRIATE SUBSTITUTES can be found for most electronic components, including variable 
capacitors. Flea markets are a good source for those components. 



since they have a certain amount of in- 
ductance that can upset the associated RF 
circuit. However, carbon-type resistors 
of the appropriate power rating can be 
used to substitute for wire-wound types. 

2. Potentiometers. Substitutes can 
usually be made having somewhat higher 
or lower values than those specified. Sur- 
plus pots can be bargains, but physical 
characteristics such as shaft length and 
type of shaft are important. Consider: Is 
the unit for screwdriver adjustment, or is 
the shaft designed to accept a knob? What 
about the pot's electrical characteristics, 
such as the "taper" — is it usable? Pots 
with "linear" or "audio" tapers are the 
types most frequently called for in con- 
struction projects. And is an on-off switch 
required on the control? 

One caution: Wire-wound pots are fre- 
quently found in surplus. Those pots are 
most suitable for low-frequency, high- 
power applications, not for delicate solid- 
state circuitry. They are not for circuits 
that require high precision (resolution). 
Thus, for most work, standard carbon- 
composition pots represent the best selec- 
tion. 

When shopping for new pots, quality is 
paramount; cheap materials are syn- 
onymous with inferior performance, 
often evidenced by a pot that is hard to 
turn because of high- friction bearings. 
Cheap imports should be avoided; stick to 
top-quality pots in all construction pro- 
jects. 

3. Capacitors. Fixed capacitors come 
in a surprising variety. There are mica. 
Mylar, silver-mica, ceramic, oil-filled, 
paper, and electrolytic types. Each has 
specific applications. Mica types (es- 
pecially silver-micas) and zero- 
tempcrature-coefficient ceramics are 
usually specified where low losses and 
high stability are essential; normally, you 



should not substitute other types for them. 
Probably the best all-round capacitor for 
general purpose use is the Mylar poly- 
styrene type — also one of the cheapest, 
and typically available for values be- 
tween 5 pF and 0.5 uF. 

Standard tolerance ratings for most 
project-grade capacitors is ± 10 to 20%, 
though for some inexpensive general- 
purpose ceramic capacitors (including 
disc types)it's as wide as -30% to 
+ 100%. Exact capacitance is relatively 
unimportant in typical bypassing/filtering 
and coupling applications, and you can 
easily deviate as much as 50% from the 
spec value without trouble, sometimes 
much more (except at VHF and UHF). 
Mylar polystyrene capacitors also run in 
the 10-20% tolerance range, with 5% 
Mylars readily available, and 2.5% and 
1% units available at somewhat higher 
prices. 

As with resistors, capacitors can be 
substituted in series or parallel to yield 
different equivalent values, though the 
combining effects are the opposite to 
those of resistors: capacitors in series act 
like resistors in parallel, while capacitors 
in parallel act like resistors in series. 

When two capacitors are placed in 
series, the total capacitance is less than 
that of either one, as determined by the 
simplified formula: 



C t = 



C1 x C2 
C1 + C2 



Capacitors are additive when placed in 
parallel: 

C, = C1 + C2 + C3 + ... 

Another handy formula is one to use 
when you need a lower value of capaci- 
tance and want to find the value needed to 
place in series with an available unit to 



obtain the desired value. That value is 
given by the formula: 



C1 



C2 



(C2/C,)-1 



The voltage-handling capability of the 
resulting capacitor chain should be con- 
sidered, as should power-handling 
capability of series/parallel resistors. A 
standard electronics text should be con- 
sulted for more on that. 

Most capacitors above I uF are alumi- 
num electrolytics and are polarized. 
Tolerances tend to be fairly loose because 
filtering and coupling applications usual- 
ly don't call for precise values. Those 
types are often available with capaci- 
tances of 100,000 u.F or more, though 
usually at very low voltage ratings at 
those high capacitances. A related though 
more expensive capacitor is the tantalum 
type. The tantalum capacitor is generally 
superior to the standard electrolytic, and 
boasts tighter tolerance, smaller size (for 
equivalent capacitance), and lower 
leakage. 

Except in specialized applications, 
such as in timing circuits where tantalums 
are generally preferred over aluminum 
electrolytics, exact capacitance isn't ter- 
ribly important. When substituting, it's 
generally wise to err on the side of too- 
high capacitance rather than too-low. 
Surplus oil-filled types can normally be 
substituted for electrolytics having equiv- 
alent characteristics. 

Substitutions are also possible with 
variable capacitors. The main con- 
siderations here relate to minimum and 
maximum capacitance. As a general rule, 
you can substitute a capacitor having a 
greater capacitance than the value speci- 
fied. It may also be possible to substitute a 
variable capacitor that has somewhat less 
range than that specified, if you can de- 
termine the actual tuning range required 
in the circuit. That involves figuring the 
amount of circuit inductance and amount 
of capacitance required for a given tuning 
range, and is best done with the aid of a 
device such as the ARRL LCF Calcula- 
tor, or using a computer. Note that junk 
box variables can be modified to become 
lower-value capacitors simply by remov- 
ing rotor plates, and multi-section receiv- 
ing variables can be paralleled to get high- 
er capacitance. 

In high-voltage circuits, be sure you 
observe maximum operating voltages 
that depend on plate spacing. Plate spac- 
ing should be equal to or greater than that 
specified by the designer, or you can refer 
to a catalog to convert spacings to 
voltage-handling capacities. Knowing 
the voltages in the circuit, you can easily 
check to see if your particular substitute is 
adequate for your purpose. 

4, Diodes. Besides resistors and capa- 
citors, you'll often be faced with making 
substitutions for diodes of various kinds, 
both rectifier and small-signal types. The 




A 20-DRAWER CABINET such as this is ideal for 
maintaining a well-organized junk box. 



former are generally specified according 
to their maximum current and reverse 
breakdown ratings. It's possible, in many 
instances, to come up with a suitable 
replacement without having to resort to 
checking a data book. The 1N414S is a 
good all-around small-signal type diode 
to have in the junk box as it is able to meet 
a wide range of substitution needs. 

5. Transistors, Besides diodes, other 
types of discrete semiconductors that 
present substitution questions include 
bipolar transistors. FET's, SCR's, and 
UJT's. As with diodes, practically every- 
one sells some transistors, but few dis- 
tributors stock each and every part num- 
ber, particularly highly specialized and 
Japanese types. 

Many transistor suppliers and man- 
ufacturers overly emphasize the difficulty 
of transistor substitution. From a prac- 
tical standpoint, the many different types 
of transistors and related economic con- 



siderations make it imperative that some 
substitutions be attempted. You'll need a 
transistor data book to determine proper 
specifications; once those numbers are 
available, you can apply them to select 
appropriate substitutes. Even using 
abbreviated substitution guides such as 
found in the Radio Shack catalogue can 
make the purchase of bargain-priced blis- 
ter-pack replacement transistors practical 
and useful. 

6. Integrated Circuits. The silicon 
chemistry of integrated circuitry con- 
stitutes a key clement of most sophisti- 
cated electronics construction projects. 
Because of their importance and wide- 
spread use. those devices are sold by most 
electronics suppliers. The devices range 
over a wide spectrum, and include linear, 
CMOS. TTL, DTL, ECL, LSI, and other 
types. The variety encountered precludes 
stocking up on any but the most common 
types. 

There is little latitude in substituting IC 
types. A circuit specifying a particular IC 
usually requires that particular IC. In 
fact, it's usually not worthwhile to sal- 
vage IC's from scrap equipment unless 
the IC's can be clearly identified and there 
is some prospect of actual use for that 
particular device. 

However, it's important to point out 
that IC designations often include 
alphabetical prefixes that simply indicate 
the device's manufacturer. There is no 
need to use an IC made by a particular 
manufacturer if the same basic device is 
available from other firms. You'll find 
that IC suffix letters aren't terribly critic- 




A MULTI -FUNCTION TEST PROBE, such as the one shown here, is handy for finding good Com- 
ponents in surplus or salvaged equipment. 



W 



m 

CO 

m 

J3 
to 

CO 

ro 
57 



TABLE I— COMPONENT SUBSTITUTION GUIDELINES 

The following constitute general guidelines for substitution of the most-used components: 
resistors, capacitors, inductors, rectifier diodes, and transistors. Refer to the text for 
discussion of otherfactors that should be considered in making parts substitutions, and for 
guidelines for other components. 



RESISTORS 

Resistance value: within ±20% of that 

specified. 
Resistance tolerance: equal to or better 

than specified, but usually not critical. 
Power rating: equal to or greater than spe- 
cified. 
CAPACITORS 
Capacitance value: within ± 20% of that 

specified, except in critical timing and 

tuning circuits. 
Capacitance tolerance: equal to or better 

than specified, but usually not critical. 
Voltage rating: equal to or greater than 

specified, ortwicethe maximum supply 

voltage. 
Type: generally not important except in 

critical timing and tuning circuits. 
COILS/INDUCTORS 
Inductance value: within ± 20% of that 

specified. 
Current rating: equal to or greater than 
specified. 



a], either. They usually indicate a change 
in the internal IC configuration that does 
not alter the basic function, though the 
suffix letter may indicate the package 
style. But, if you find a letter (or two) 
inserted between some of the numbers, it 
may indicate a significant modification 
that precludes easy substitution. In such 
cases, it's wise to consult a data book, 
paying particular attention to possible 
changes in pin numbering. 

7. Power transformers and chokes. 
When your project requires a very specif- 
ic transformer, it may be best to order it 
directly from the manufacturer or his dis- 
tributor. 

On the other hand, if specs aren't too 
tight, or it's possible to connect windings 
in various configurations to obtain re- 
quired voltages, it may pay to take advan- 
tage of specials and closeouts by mail- 
order distributors — though transformer 
offerings are usually limited in variety. 
Industrial surplus dealers generally have 
the best selection; transformers with the 
most unusual characteristics can turn up 
in surplus. 

One of the main considerations in mak- 
ing transformer substitutions is adequate 
current/power handling capacity. You 
can substitute if the transformer in ques- 
tion has the same voltage rating with more 
w current-carrying capacity, but it's risky to 
^ go the other way . However, if the trans- 
O former is rated in terms of continuous 
h duty, and its intended use will be in- 
uj termittent, a rating reduction of up to 
Qj about 25% may prove to be quite accept- 
ed able. 

g Minor primary and secondary voltage 
cc substitutions can be made without 

58 



RECTIFIER DIODES AND 
BRIDGE ASSEMBLIES 

Current rating: equal to or greater than 

specified. 
Reverse breakdown voltage: equal to or 

greater than specified. 
TRANSISTORS 

Type: as specified (PNP or NPN, etc.). 
Collector current rating (l c ): equal to or 

greater than specified. 
Reverse breakdown voltage: equal to or 

greater than specified. 
Gain (Beta orhfj: equal to or greater than 

specified. 
Power rating: equal to or greater than spe- 
cified. 
Cutoff frequency: equal to or greater than 

specified. 
Case style: usually not important. 

NOTE : A transistor data book must be con- 
sulted for determining most of the 
specifications necessary for mak- 
ing substitutions. 



adverse effect. If you have a transformer 
that delivers a higher voltage than you 
want, you can drop the voltage with a 
series resistor or a voltage-divider 
system. 

As for power-supply chokes, sub- 
stitutions are usually easy. The specified 
value of a filter choke can usually be 
regarded as a minimum value. The in- 
ductance of chokes in series is additive; 
conversely, chokes in parallel function 
like resistors in parallel. The amount of 
capacitance required in a power supply is 
affected by the power-supply choke in- 
ductance — the choke and electrolytic 
capacitor work together to bring ripple 
down to an acceptable level. 

In addition to inductance ratings, you 
must also take into account the current the 
choke must carry. Of course, you can use 
a choke with a higher current rating than 
specified. Using a somewhat lesser-rated 
choke is probably OK, unless the choke is 
rated at less than 75 % of expected cur- 
rent. The inductance becomes less if more 
current is drawn through the choke than 
the unit is rated for, thus reducing the 
choke's filtering effectiveness. 




A DESOLDERING TOOL makes removing parts 
from a surplus or salvaged piece of equipment 

simple. 



8. Switches. Substituting switches 
can be tricky because of the numerous 
possible switching configurations and ap- 
plications. You can always use a switch 
that has more contacts or sections than are 
required for a given circuit, as long as it 
has an adequate voltage rating. Often that 
information can be obtained from man- 
ufacturers' and distributors' catalogs. 
Similar considerations apply to relays, 
but selection criteria are complicated by 
relay coil voltage and current, and other 
operating characteristics. 

9. Tubes. Most contemporary circuit- 
ry has abandoned the once-common 
vacuum tube, though a few tube designs 
survive, and there is still demand for 
tubes for replacement purposes. Tubes 
are becoming extremely expensive and 
difficult to find, and few are still man- 
ufactured in the United States. One good, 
low-cost source of once-common receiv- 
ing tubes is Cornell Electronics Com- 
pany, 4217 University Avenue, San Di- 
ego, CA 92105; the firm stocks a wide 
variety of bargain -priced receiving tubes. 
Radio Shack also provides a special-order 
service that includes about 2000 different 
types. If you don't have the tube you 
need, of course, you'll have to buy it. But 
a quick check of a tube-substitution man- 
ual, or the ARRL's Radio Amateur's 
Handbook (it lists different tube types and 
possible substitutions if available) may 
prove worthwhile. 

10. Other components. There are 
many other components that the project 
builder will find useful to keep in his junk 
box or bench stock for the purpose of 
convenient substitution in construction 
projects. 

We can't treat all of them here. But 
some that come to mind include plugs, 
jacks, audio and IF transformers, transis- 
tor and IC sockets, battery clips, ter- 
minals, hardware, alligator and crocodile 
clips, meters, connectors, chassis, PC 
boards, and cabinets. 

In many instances your best guide to 
making intelligent substitutions is sim- 
ple, ordinary common sense, as well as an 
understanding of when not to use sub- 
stitute parts but to go out and acquire a 
specified part. 

Getting into the practice of breadboard - 
ing project circuitry will not only help 
refine a circuit before commitment to a 
final design, but will make substitutions 
easier because it gives you a chance to 
double-check your choices. Soldcrless 
breadboards eliminate a great deal of the 
trouble involved in circuit development 
and make desk-top experimentation — 
and substitution — much easier. 

Table 1 lists popular component sub- 
stitution considerations in tabular form. 

When we continue this article, we'll 
take a closer look at where you can obtain 
your parts for projects. Among the topics 
we'll cover will be how to successfully 
use surplus and salvaged parts, including 
how to test and identify them R-E 




D 




cr— i 



A U 




How to Design 

Analog Circuits 

- Biasing Transistors 




Proper transistor operation depends on 
proper biasing. Learn ail about biasing 
circuits and how to design them in this 
month's article. 



O s 



Part5 



LAST MONTH, WE BEGAN 

our discussion of bipolar 
and FET transistors by looking at the struc- 
ture of those devices and at some basic tran- 
sistor circuits. One of the things we men- 
tioned was that if a bipolar device were used 
in a Class A common-emitter circuit, for 
linear operation the collector voltage (with 
no input signal present), should be set atone 
half the supply voltage. The no- in put -signal 
condition is commonly referred to as the 
quiescent operating point. (Similarly, in the 
case of an FET in a common-source circuit, 
the drain voltage should be one half the 
supply voltage). That, however, is merely 
an approximation; the actual operating point 
varies with the specific requirements of the 
circuit. In any event, once the proper op- 
erating point has been selected, the device 
must be biased for that point. Just how that 
is done is the topic of this month's article. 

Bipolar transistors 

There are essentially two types of bias 
circuits that are used with bipolar devices. 
Although there may appear to be many 
more, the others are simply variations of 



those two circuits. And even the two cir- 
cuits arc variations of each other. 

But why do we need many bias cir- 
cuits? They arose mainly because of the 
high leakage current, Icno> 'hat flowed 
from the collector to the base in early 
germanium transistors. If that leakage 
current also flowed through the base- 
emitter junctions (as it normally did), it 
was multiplied by beta (B) to make it into 
a large undesirable leakage current, Iceo» 
that flowed in the collector and emitter 
circuits. And to compound the problem, 
Icbo and I ceo doubled every time the 
temperature of the transistor increased by 
I0°C. Although those factors are still im- 
portant in modem silicon transistors, the 
effect on the collector current is reduced 
considerably because the leakage current 
in silicon transistors is frequently low 
enough to be ignored. 

In addition to leakage current, var- 
iations in the operating parameters from 
device to device, as well as with tempera- 
ture, can cause problems. The value of 6, 
for instance, will vary from device-to- 
device of the same type, as well as with 




MANNY HOROWITZ 



temperature and collector current, I c . In 
addition, the value of I c at the operating 
point will vary with several parameters. 
Among those are V IJE , the voltage drop 
across the base-emitter junction, which 
itself varies with temperature; V BB , the 
base supply-voltage; r c , the collector-to- 
base resistance in a common-base circuit, 
and rj the collector-to-base resistance in 
either a common-emitter or common- 
collector circuit. 

But, once the operating point has been 
established for a circuit, ideally it should 
not be effected by differences in parame- 
ters from device-to-devicc, or by any ex- 
ternal factors such as temperature. That is 
the reason for all of the bias-circuit var- 
iations — they are designed to help stabi- 
lize the operating point. In theory, if the 
proper bias circuit is used, the operating 
point will not change regardless of any 
change in any of the factors mentioned. 
However, theory and what really happens 
are not always the same. But even so, 
using the proper bias circuit will 
minimize any variations of the operating 
point sufficiently so that the circuit will 



w 
m 

m 

CD 

m 

<D 
oo 

ro 

59 



still operate as intended. 

To design a bias circuit properly, it is 
important to know how a variation in one 
variable will effect the other variables in 
the circuit. Because of that, three stability 
factors that relate the change of one factor 
to the change in another have been de- 
rived. They are: 



o 

z 
o 
ir 

H 
O 



Q 
< 
DC 



Ale 



Ale 



(D 



which relates the change of collector cur- 
rent to the change in leakage current. The 
stability factor relating the change of col- 
lector current to the change in V BB is: 



S e = 



Ale 



AV B 



(2) 



while the equation relating the collector 
current change to the change in & is: 



S„ = 



Ale 
Ap 



(3) 



Equations used to relate the various 
components in the circuit to the various 
stability factors, will be noted as each bias 
circuit is described. In each case, it is 
desirable that stability factors be as close 
to 1 (the perfect stability factor) as possi- 
ble. Should more than one stability factor 
differ from I , the effects of all variations 
must be taken into account when evaluat- 
ing the design. 

Bipolar transistor bias circuits 

The simplest bias circuit to be de- 
scribed here is shown in Fig. 1 . The base 
current, I B , originates at V BB and is deliv- 
ered to the base through R B . However, 
V BB often does not exist as an in- 
dependent supply; instead V cc is used to 
supply both base and collector current . In 
that case, R B is connected to V cc , and 
that supply serves as both V cc and V BB . 

In Fig. 1, all base current from V BB 
flows through the base-emitter junction. 
If we consider the voltage across that 
junction, V BE , as negligible when com- 
pared to V BB , the base current due to the 
supply is V BB /R B . Collector current due 
to that base current is approximately 
equal to BI B . 

Next, let us add the effect of 1 C bo> the 
leakage current that flows from the col- 
lector to the base. After flowing through 
the base-emitter junction, it is multiplied 
by beta. That BI C bo flows in the collector 
and emitter circuits and substantially 
effects the collector and emitter currents. 
Collector current due to I CBO is thus 
PIcbo = 'ceo- (Note that in our dis- 
cussions beta has been assumed to be 
much greater than I. Thus only B is 
shown in formulas rather than 3 + 1 .) 

Finally, we have some collector cur- 
rent flowing due to r d , the collector-to- 



1 i 



FIG. 1— A SIMPLE CIRCUIT for biasing bipolar 
transistors. Often there is no separate V BB 
supply; instead V cc Is used to supply both the 
collector and base. 



emitter resistance of the transistor. That 
resistance can be determined from the 
co m m o n - e m i Her c oil e ctor-characteri sties 
curve shown in Fig. 2. Using the pro- 
cedure described in our last article (see 
the August 1982 issue of Radio- 
Electronics, draw the load line on the 
curve. The next step is to determine the 
operating or quiescent point needed to 
insure linear operation. If, for instance, 
you require that the collector current 
swing from to Ic(max> the collector 
current at the quiescent operating point, 
Iccj. would be equal to Ic(max/2. Find 
that point on the I c axis. The voltage at 
the quiescent point, V CE0 , is usually 
equal to about V cc /2. Drawing a line 
perpendicular to the I c axis at I C q, and a 
line perpendicular to the V CE axis at 
Vceqi the point at which the two lines 
cross is the operating point. As drawn, 
that point falls on the I B = 100 /iA curve. 
Collector resistance, r d , is the slope of 
that I B curve around the operating point. 
The slope is found by noting two points 
that are equidistant from the operating 
point, and finding l c and V CE for those 
points. Assuming that the collector volt- 
age and current at one point are V CE , and 
I CE j , and V CE2 and I C E2 at the other, then: 



^ = 



- V c 



(4) 



As indicated, r d is the collector-emitter 
resistance of the transistor when it is used 




FIG. 2— ONCE THE QUIESCENT POINT has been 
found, the value of r d is equal to the slope of the 
l B curve around that point. 



in a common-emitter or common- 
collector circuit. In a common-base cir- 
cuit, that collector-emitter resistance is 
much higher and equal to Br d ; that quan- 
tity is called r c . 

A portion of the total collector current 
is due to the presence of r d in the circuit. It 
is equal to the collector-emitter voltage, 
V CE , divided by r<j. Obviously, V CE is 
equal to the supply voltage less the volt- 
age drop across the collector resistor, R D , 
or V cc — I c Rc- Consequently, the total 
quiescent collector current flowing in the 
circuit of Fig. 1 is: 



b = pla + Iceo + 



'cc ~~ >c"c 



which simplifies to: 

pl B + Iceo + V cc /r d 



l<: 



IVr d + 1 



(5) 



Should R c be less than 10% of r d , the 
effect of r d becomes negligible, and all 
factors in the equation involving that term 
can be eliminated. We will then end up 
with the simple relationship: 

Ic = P'b + 'ceo 

Finally, remembering that I B = V bb /Rb, 
we get: 

p(V BB + R B l CBO ) 

,o = s: < 6 > 



You can usually use equation 6 and 
ignore r d in most designs. But do not 
forget about r d . It will be important later 
on when we discuss AC gain and the 
output impedance of transistor circuits. 

The various stability factors for the cir- 
cuit shown in Fig. 1 are: 



s = p 


(7) 


Se = P/R B 


(8) 


lcBOi"B "+■ ^bb 





(9) 



Equation 9 indicates by how much the 
collector current will change for a specific 
change in B. Thus if a transistor with a B 
of 80 is substituted for one with a B of 40, 
the quiescent collector-current will dou- 
ble. To see how we came to that conclu- 
sion, let's digress a bit. First, as we saw in 
equation 3, S fl = AI C /AB. Expanding 
further, equation 3 can be rewritten as 
AI C = Ap(I B ). Secondly, since I CBO is 
generally small enough to be ignored, and 
since V BB /R B is equal to I B , in this case, 
the stability factor, SB, defined by equa- 
tion 9 is approximately equal to I B . Thus 
AI C = AS(I B ). Originally, I t - was equal 
to the inital |3 of 40 multiplied by I„, or 
40I B . If AB = 40, and AI C = ABI B , then 



60 



AI C = 40I B . Finally, the total collector 
current when p is increased from 40 to 80 
is l c + Ale, or40I B + 40I B = S0I B . 

Improving stability 

Stability can be improved by adding an 
emitter resistor, R E , to the circuit in Fig. 
1 . If that is done, equations 7,8, and 9 are 
modified to become; 



"cc 



P(R E + R B ) 
PR E + Rb 



PR 6 + R B 



{10) 



(11) 



(R E + R B ) V BB + leso Rb (Re + Rb) 



<PR E + R B ) £ 



(12) 



In this arrangement, base current is less 
than it was when there was no emitter 
resistor. It is reduced because the emitter 
resistor, R E , is reflected into the base 
circuit as a resistor equal to pR E . Because 
of that, the base current becomes (V BB / 
(R B + pR E )) + I C bo- In addition, I c 
becomes equal to B1 B . 

The bias circuit shown in Fig. 3 is used 
when stability is a very important con- 
sideration. The circuit in Fig. 1, and the 
variation we created by adding an emitter 
resistor, are simplified versions of that 
circuit. In it, V BB has been eliminated: 
instead, V cc is used as both the collector 
and base supply. 

Thevenin's theorem must be used in 
order to determine the base current in the 
circuit in Fig. 3. That theorem states, in 
part, that any network of voltage sources 
and resistances can be simplified to a sin- 
gle voltage source in series with a single 
resistance. Use the following steps to 
apply that theorem to the circuit. Those 
steps are shown in Fig. 4. 

First, as shown in Fig. 4-a, separate the 
bias resistor circuit from the rest of the 
circuit. 

The second step, as shown in Fig. 4-b, 
is to determine the voltage at the junction 
of R B and R x . That voltage is called the 
Thevenin voltage, V-^, and, since R B and 
R x make up a simple voltage divider, is 




FIG. 3— IF BETTER STABILITY IS REQUIRED, 
the bias circuit shown here can be used. 



M © 

■I' 




I ^TH a X ^ B 
_R X R B 



R X + H B 




FIG. 4— TO EVALUATE THE BASE CURRENT of the circuit shown in Fig. 3, Thevenin's theorem must 
be used. The steps followed in applying that theorem are shown here. 



equal to V CC (R X /(R B + Rx))- 

The third step, as shown in Fig. 4-c, is 
to short the supply to ground and de- 
termine the Thevenin resistance, R TH - 
That is the resistance seen when looking 
back toward R x ; in other words, the re- 
sistance between the junction "J" and 
ground. In this case, it is the parallel 
combination of R x and R B , which, of 
course, is equal to R X R B /(R X + R B ). 

The fourth, and final step, shown in 
Fig. 4-d, is to reconstruct the original 
circuit, substituting V-,^ for V C c» and 
R TH for R B and R x . The Thevenin volt- 
age, V TH and the Thevenin resistance, 
R TH , are connected in series with the base 
of the transistor as shown. The base cur- 
rent can now be calculated from the for- 
mula: 



l. 



factors, a desirable result. In determining 
the operating point, the simplest 
approach is to again use Thevenin's 
theorem. Just adapt the method described 
for the circuit in Fig. 3 to this circuit, 
using the value of V CE that you are de- 
signing for instead of V cc . A reasonably 
accurate formula for determining col- 
lector current is shown as equation 13. 
Note that R c and I CB o are included in the 
equation. Stability factors for this circuit 
are shown in equations 14, 15, and 16. 

. P[RxV cc + lcso(A + RxR B )] 

-■ - 03) 



S = 



pR 6 



The value of V BE is usually .017-volt 
for a silicon transistor, and 0.2- to 0.3- 
volt for a germanium device. Once 
you've calculated I B , the collector current 
is simply |3I B . 

In this type of circuit, the effect of 
leakage current, Icbo- ' s reduced because 
some of it is diverted from the base- 
emitter junction to R x . A good rale of 
thumb to use when designing this type of 
circuit is to make R x equal to less than ten 
times the size of R E . 

As we mentioned earlier, there are two 
basic types of bias circuits. So far, all of 
the circuits we've examined were var- 
iations of one type. Let's now turn our 
attention to the second type. It is shown in 
Fig. 5, Here, R B is connected to the col- 
lector of the transistor being biased in- 
stead of to Vcc- 1° tnat circuit, negative 
feedback from the collector to the base 
acts to reduce the value of the stability 



pA + R x R e 



P(A + R X R B ) 
PA + R X R B 



PRx 
PA + R X R B 



(14) 



(15) 



(RxVcc + RxRbIc8o)(A + R x R b ) 



(PA+R b Rx) 2 



(16) 



Where A 



H B Hc "h H B H B + R^nx "^* 

RxRc)- 



Those current and stability equations 
can be applied easily, with just slight 
modifications, to the circuit in Fig. 3. In 
equations 13 through 16, R c is an impor- 
tant factor in determining the bias. It 
plays no part, however, in determining w 
the stability and quiescent current for the [[J 
circuit in Fig. 3. When applying those ^j 
equations to that circuit, let R c equal 0. S 
That eliminates all terms containing R c . m 
If, in addition to setting R c equal to 0, R x ^ 
was made infinite by removing it from the g 
circuit and R,. ; was made equal to 0, or M 

G1 



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FIG. 5— THIS CIRCUIT is one of the many var- 
iations of the two basic bias circuits. 



shorted, we end up with equations 6 
through 9; those were, as you recall , used 
for the circuit shown in Fig. 1 . Should R E 
be left in the circuit, the equations will be 
identical to equations 10, 11, and 12, 
Thus, equations 6 through 12 are simply 
variations of equations 14, 15, and 16. 
There are many variations of the simple 
circuits we have presented thus far. One 
of those is to remove R x from the circuit 
of Fig. 5. That does reduce stabili- 
ty somewhat, however. Equations 13 
through 1 6 still apply, but are modified by 
removing all terms containing the expres- 
sion R x . 

Temperature compensation 

Base-emitter voltage variation with 
temperature is an important considera- 
tion, especially in power circuits, be- 
cause in those the temperature of the tran- 
sistors tends to increase by a considerable 
amount. The circuit most-commonly 
used to compensate for that is shown in 
Fig. 6. 

Diode D is placed into the circuit as 
shown so that it is always on. The diode 
used should have the same voltage/ 
temperature characteristic as the forward 
biased base-emitter junction of the tran- 
sistor. It should also be placed close to the 
transistor so that both of their tempera- 
tures will vary in a similar manner. With 
this configuration , the voltages across the 
diode and the base-emitter junction are 
always identical. Because of that, the 
voltage across R E and R x are also always 
identical, regardless of any changes in 
V BE caused by temperature. Thus stabil- 
ity is improved. 

The final variation we'll discuss here, 
is the one shown in Fig. 7. In most bias 
circuits, R E is connected between the 
emitter and ground. Here, however, a 
battery or other voltage source, V EE , is 
inserted between the emitter and ground. 
As a result, the base current, I B is approx- 
imately equal to V EE /(R X 4- SR E ); the 
collector current, as usual, is equal to 
BI B . The stability factors for that circuit 
are essentially the same as those calcu- 
lated using equations 10 through 12, 
When applying the equations here, 



FIG. 6— TO COMPENSATE for variations caused 
by temperature, a diode can be placed in the 
base circuit as shown. 




FIG. 7— IN THIS VARIATION, a battery or other 
voltage source Is Inserted between the emitter 
and ground. 



however, substitute V EE for V cc , and R x 
for R B . 

In summary, as a general procedure 
when designing bias circuits, first de- 
termine the ideal quiescent collector 
voltage and current. Divide the collector 
current by (3 to find approximately what 
the base current should be. Next design a 
base circuit to establish those conditions. 
Remember that those conditions should 
be relatively insensitive to temperature 
changes, as well as parameter variations 
from device to device. To make certain 
that they are, you must check the stability 
factors. Any of the circuits we've dis- 
cussed, as well as many other variations, 
can be used when biasing bipolar transis- 
tors. You must determine how much op- 
erating point instability your design can 
tolerate. Start with the simplest circuit 
and calculate the stability factors. If col- 
lector current variations due to these fac- 
tors are too great, increase the complexity 
one step at a time. Never go beyond the 
simplest circuit you can use to satisfy 
your requirements. 

Biasing JFET's 

Gates of n-channel JFET's are usually 
made negative with respect to the source. 
But, as no gate current flows if the gate is 
made just slightly positive with respect to 



the source of a JFET, up to +0.5 volt 
may be placed at the gate. Two arrange- 
ments used for establishing the proper 
bias voltage are shown in Fig. 8. 

In Fig. 8-a, drain current, 1 D , flows 
through R D and R s . Thus, the source cur- 
rent, I s , and I D are equal to each other. A 
voltage equal to I n Rs is developed across 
R s . That voltage is called V RS and has the 
polarity shown. 

A leakage current, loss, flows from the 
gate to the source. The value of I GSS at 
25 °C is often found on the specification 
sheets of the device. That leakage cur- 
rent, however, increases with tempera- 
ture — usually doubling with each in- 
crease of 10°C. The leakage current flows 
through R G . developing a voltage, V RG 
equal to I G ss r g- The polarity of that vol- 
tage is also shown in Fig. 8-a. 

Voltage between the gate and source is 
equal to V RS — V RG . The value of V RS is 
usually adjusted to be larger than the 
value of V RG so that the gate will be 
biased negative with respect to the 
source. That's how the bias for the circuit 
shown in Fig. 8-a is established. 





FIG. 8— EITHER OF THESE CIRCUITS can be 
used when biasing either JFET's or MOSFET's. 



The source resistor is an important fac- 
tor in enhancing the stability of the circuit 
as it is used to counteract any increase of 
I GSS caused by a change in temperature. 
Circuit stability can be improved by in- 
creasing the size of R s . But there is a limit 
to this. Should R s be increased too much, 
the voltage developed across it can be 
high enough to bias the transistor near or 
at pinch-off. That is, of course, undesir- 
able. The value of the source resistor must 
be chosen so that the proper bias point is 
established when the voltage developed 
across R is subtracted from the voltage 
developed across R s . 

A larger source resistor can be used 
with the circuit shown in Fig. 8-b. In that 
circuit, a sizable positive voltage can be 
developed across R G due to the presence 
of +V DD and the action of the voltage 
divider made up of resistors R x and R G . 
That positive voltage is increased some- 
what by the presence of leakage current 
loss- To determine the gate-to-source 
bias voltage, subtract the voltage de- 

coniinued on page J 02 



^^^^m^^^^m 




WMJMW. 








Add an extra dimension to your recorded music with this Stereo Image 
Expander. Build it and hear what you've been missing, 



JOEL COHEN 



Part 2 



IN THE FIRST PART OF 

this article, we looked 
at the theory behind the Stereo Image 
Expander. This time we'll apply what 
we've learned and build our own. 



Assembly 

A foil pattern for the expander PC- 
board is shown in Fig. 1 1 , and a parts 
placement diagram in Fig. 12. Figure 13 
will also help you in completing the 
board. Some of the instructions here per- 
tain specifically to the parts supplied with 
the kit available from the supplier in- 
dicated in the Parts List, but may also be 
applicable to you if you're building from 
scratch. 

Pin 1 of each IC is indicated by an 
indented dot and all but IC5 are mounted 
with pin 1 facing towards the rear of the 
board. The bucket- brigade device, IC6, 
is subject to damage from static charge — 
it's a good idea to be sure that you are 
grounded before handling it. The use of 
IC sockets is recommended. 

The BBD, incidentally, can be either 
an SAD512 or SAD 1024— the pinouts 
are identical. The SAD 1024 contains two 
SAD512's, and one of them will simply 
not be used. 

Be sure to observe the polarities of the 
electrolytic capacitors and diodes. Note 
that regulators IC1 and IC2 are mounted 



with their center leads bent back toward 
the curved part of the package, while the 
transistors they resemble have their cen- 
ter leads bent slightly forward, toward the 
flat sides of the packages. Don't forget 
the two jumpers shown in the parts place- 
ment diagram. 

The transformer must be installed with 
pins 1 and 2 toward the rear of the board. 
Bend the two mounting tabs away from 
the transformer and solder them to the foil 
side of the board. If you are using the 
phono jacks provided by the supplier 
shown in the Part List, cut off the plastic 
tabs at their rear comers before attaching 
them and be sure they are firmly seated 
parallel to the board before soldering. The 
switch bodies must be spaced .093-inch 
above the top of the board if the cabinet 
supplied with the kit is used. If the switch- 
es do not have shoulders on their mount- 
ing pins, use three plastic spacers over the 
pins at the front of S3 and the rear of S I 
and S2. Be sure the switches and image 
control are seated parallel to the board so 
they will fit into the holes in the chassis. 

To mount the LED, bend its leads at a 
90° angle while holding it towards you 
with the anode lead on your right. Solder 
it in so that the bend is '/i-inch above the 
top of the board. Install the completed 
board in its enclosure, and attach the line 
cord. Be careful of stray strands of wire. 



especially near the grounded board- 
mounting screw at the rear corner. 

Alignment 

Only one adjustment is required; the 
BBD bias which is set by R7. There is 
about a 2-volt window for signals to pass 
through the BBD and the bias is set for the 
center of that range so that the maximum 
peak-to-peak signal can pass through 
without clipping. There is enough head- 
room in the design of the expander to 
allow for individual IC variations if the 
bias is simply set to +3.5 volts. 

!f you want to "fine tune" the ex- 
pander, apply about 1.5-voIts RMS at 1 
kHz to just the left input and observe the 
waveform present at jumper J 1 . If the bias 
is too high, the top of the sine wave will be 
clipped; if it's too low, the bottom will be 
clipped. At the optimum setting the wave- 
form will be just slightly clipped at both 
top and bottom. 

Rooms and loudspeakers 

While most of us would find it difficult 
to tell the difference between one ampli- 
fier and another by ear, we all know that 
different speaker- systems have different 
qualities and that the sound from a par- 
ticular system can vary depending on 
where it is located in a room. Most of the 
sound energy reaching our ears comes not 



m 

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CD 

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to 
go 




6-5/8 INCHES- 



FIG. 11— STEREO IMAGE EXPANDER is constructed on single-sided PC board. The use of IC 
sockets Is recommended. 



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64 



directly from the speakers, but from 
secondary reflections of the sound from 
the walls, floor, and ceiling. The frequen- 
cy response of that sound energy is 
shaped by the absorption characteristics 
of the surface it reflects from. The stereo 
image, however, is formed entirely by the 
first-arrival sound traveling directly from 
the loudspeakers to our ears. 

Several conditions are needed for a 
good stereo image, and they arc the same 
whether that image is expanded or not. 
First, the listening position must be the 
same distance from each speaker so that 
each ear hears its own speaker first. It is 
also helpful to point the speakers in 
toward the listening position. Second, the 
first-arrival sound from the speakers 
should precede the arrival of the first re- 
flected sound by as long a time as prac- 
tical, with one or two milliseconds being 
the minimum. That usually requires that 
the speakers be two feet or more from any 
wall or large piece of furniture and no 
more than 1 or 1 2 feet from the listening 
position. Third, the two speakers should 
be separated by an angle of 40°; that is, an 
imagincry line drawn to each speaker 
should form a 20° angle with one drawn 
from the listener to a point directly be- 
tween them. That means that the distance 
between the centers of the two speakers 
should be 7/10 of the distance from each 
speaker to the listening position. Fourth, 
the speakers must be connected in phase. 
The easiest way to test that once they are 
positioned is to tunc in some FM intersta- 
tion hiss or a monophonic program. If the 



PARTS 
All resistors 1 /4-watt, 5%, unless otherwise 
specified 

R1, R6, R14, R16, R17— 1000 ohms 

R2, R4. R25, R26. R30. R31— 100,000 oh rns 

R3, R5— 47,000 ohms 

R7. R15, R23, R24, R27-R29— 20,000 ohms 

R3, R5— 47,000 ohms 

R7, R15, R23, R24, R27-R29— 20,000 ohms 

R8— 100,000 ohms. PC-mount potentiom- 
eter 

R9. R13— 4.7 ohms 

R10, R20, R22, R34— 4700 ohms 

R1 1—100 ohms 

R12— 2000 ohms 

R18, R19— 10,000 ohms 

R21— 100.000 ohms, potentiometer, 
audio taper 

R32, R33— 390 ohms 

Capacitors 

C1, C2— 470 ^F, 35 volts, electrolytic 

C3, C4, C6-C8, C12— 0.1 „f, ceramic disc 

C5 — 47 nF, 16 volts, electrolytic 

C9, C17. C18— 0.01 hF, axial ceramic or 
ceramic disc 

C10, C13, C16— 10 «F, 16 volts, electrolytic 

C1 1—100 pF, axial ceramic or ceramic 
disc 

C14 — 390 pF. axial ceramic or ceramic 
disc 

C15 — 1500 pF. axial ceramic or ceramic 
disc 

Semiconductors 

IC1— LM340L15. 15-volt positive regulator 



speakers are in phase the sound will 
appear to come from a point directly be- 
tween them. If they are out of phase, it 
will seem to come from the sides, or from 
each speaker individually. If the apparent 



LIST 

IC2— LM320L15. 15-volt negative regulator 
IC3, IC4— MC4558 dual op-amp 
IC5— CD4049 CMOS hex inverter 
IC6— SAD512 or SAD1024 N-channel 
bucket-brigade device (Reticon. Also 
Radio Shack 276-1761.) (See text) 
Q1. Q2— 2N2222, 2N3904 or similar 
D1-D4— 1N4002 or 1N4003 
LED1— jumbo red LED 
T1— 35 volts, center-tapped, PC-mount 

(Dale PL-12-09 or similar) 
S1-S3— pushbutton switch assembly: 3 
DPDT or 1 DPDT, 2 4PDT (Schadow F- 
series or Centralab PB20-series) 
J1-J8— RCA-type phono jack, right-angle 

PC-mount 
Miscellaneous: PC board, IC sockets, en- 
closure, line cord, strain relief, hardware, 
etc. 

The following are available from Sound 
Concepts, Inc., P.O. Box 135, Brookllne, 
MA 021 46: assembled and tested IR2200 
stereo image expander, S1 69,00: kit of all 
parts (KIR-1), $95.00; PC board (KIR-2), 
$16.00; T1 (K!R-3), $7.50; all pots, knobs, 
switches and lacks (KIR-4), $12.50; all 
semiconductors and sockets for them 
(KIR-5), $19.00. Please add $2.00 for 
shipping and handling; MA residents add 
5% sales tax. If at all possible give street 
address for UPS delivery. Please add 
10% ($5.00 minimum) for parcel post out- 
side contintental U.S.A. 



source is diffuse, the speakers should be 
repositioned as described above and 
again checked for phasing. 

Finally, the speakers themselves must 
produce a sharp coherent wave-front. 



117 VAC 



TAPE 
OUT 

A 



IN FROM 
PREAMP 







LED1 

FIG. 12— PROVISION 15 MADE for mounting right-angle input and output jacks directly on 
board. 



Two- and three-way speaker systems 
with a single in-line vertical array of driv- 
ers usually work best. Omnidirectional 
speakers, or those with multiple drivers 
covering the same frequency range, can- 
not create as sharply focused an image. 
You can actually check all this out be- 
fore trying an image enhancer. Using a 
mono signal to get a tightly focused single 
sound-source located between the speak- 
ers is the best and easiest way to judge the 
imaging capability of your speakers in 
your listening room. Once you are set up 
correctly, you will probably be impressed 
with how much better your stereo system 
sounds — even without expansion. 

Installation and use 

The stereo image expander is intended 
to be connected in the tape-monitor loop 
of your preamplifier or receiver. Provi- 
sion is made in the expander for connect- 
ing a tape recorder. The recorder can be 
used in the normal manner when the pre- 
amp's tape-monitor switch is on and S 1 of 
the expander is in the tape position. Im- 
age-enhanced tapes that can be played 
back without the expander can be made 
when S3 is in the rec position. You 
should never have S 1 and S3 pushed in at 
the same time since that effectively con- 
nects the recorder's output back to its 
input. 

The recorder-output jacks from your 
receiver or preamp should be connected 
to the input from preamp jacks, Jl and 




FIG. 13— NOTE HOW LED is mounted above 
the board, not flush with it. All components 
including transformer and switches, are sol- 
dered to board. 



J3 , on the expander and the output to 
preamp jacks, J6 and J 8, to your tape- 
input or tape-monitor jacks. The expand- 
er's tape output jacks, J5 and J7. are 
connected to the line-input jacks on the 
recorder and its line -output jacks con- 
nected back to the tape input jacks, J2 
and J4, on the expander. 

If you are using two tape-loops and two 
recorders, place the expander in loop 2. 
To play unenhanccd tapes through the 
expander, use the tape-monitor switch 
corresponding to the loop the recorder is 
in. With S 1 in the tape position, the sig- 
nal comes directly from the recorder con- 
nected to the expander, and in the source 



position the signal is supplied by the re- 
ceiver or preamp. If the expander is in 
loop 2 and you want to listen to the re- 
corder in loop I , either engage both tape 
monitor switches or — if you have them — 
the tape monitor 2 and dub i to i 
switches on the preamp or receiver. 

If you have other signal processors in 
your system the expander should be the 
last one in the chain so that there is a 
minimum loss of phase integrity. If, for 
example, you already have an equalizer in 
your tape loop with a recorder plugged 
into it, plug the expander into the equaliz- 
er's tape jacks and the recorder into the 
expander's tape jacks. The expander can 
also be connected to the external- 
processor loop or between the preamp and 
power amp if you don't wish to use it for 
recording. 

Listening 

Before you make a critical evaluation 
of the stereo image expander's capabilit- 
ies, make sure your system is set up as 
described earlier. Start with a record or 
tape of a good live or concert hall per- 
formance, preferably of a large orchestral 
work so you have a realistic frame of 
reference. (Most of the recent Telarc rec- 
ords have excellent imaging.) You may 
want to turn up the image level slightly 
with some other records, particularly 
those that were originally recorded using 
multiple-mike techniques and whose 
continued on page 91 



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■■ 



Troubleshoot 
and Repair 
Portable 



Cassette Recorders 




HOMER L. DAVIDSON 



PORTABLE CASSETTE PLAYERS AND REC- 

orders (the ones that use standard Philips 
cassettes, not to be confused with mini- or 
micro-cassette devices) can be repaired as 
easily as any other tape units. Don't be 
afraid of their small size — the com- 
ponents may be a little closer together and 
you may have to work in a tighter space, 
but that's all. Servicing them can be easy 
when you follow the tips and information 
here. 

Lf you have a well-equipped work- 
bench you shouldn't need much in the 
way of additional equipment. If you don't 
have one, a take-up torque gauge may be 
needed for mechanical components, A 
VTVM (Vacuum Tube Volt-Meter) will 
do nicely for making head-azimuth 
adjustments, and for troubleshooting the 
amplifier section, you can use your signal 
generator, signal tracer, and scope. 

Cleaning and lubrication 

Most sound and speed problems can be 
solved by a good clean-up and "lube 
job." A dirty record/ playback head may 
be responsible for weak and distorted 
sound, and under- (or over-} lubrication 
can cause tape-speed to vary erratically. 

When a recorder develops speed or 
sound problems, it's time for a cleanup 
and lubrication. Start at the erase and 
record/playback heads and clean them 
with alcohol and a soft-tipped cleaning 
stick. Critical points for cleaning are 
shown in Fig. I . Do not use rubbing alco- 
hol — it contains an additive that may 
leave a gummy deposit. Use pure iso- 
propyl alcohol (available at your drug- 
store's prescription counter). If some ox- 
ide is packed into the gap area of the 
record/playback head, gently use the 
round end of [he cleaning stick to remove 
it. You can get at the heads easily by 
putting the recorder in the record mode; 
that moves them out into the open. 





FIG. 1— CRITICAL POINTS FOR CLEANING are indicated above. A good cleaning can be all 
that's needed to solve many problems. 



G6 





Don't let their size scare you — small, portable 

cassette recorders are as easy to troubleshoot as 

their larger brothers. Here are a number of hints and 

kinks to help you out. 






You may find more oxide on the pinch 
roller and capstan than on the tape heads. 
Remove it with alcohol . Apply a drop of 
light oil to the pinch-roller bearing and 
wipe off any excess. Also, always dry off 
parts that have been cleaned with alcohol 
since it can damage many rubber and 
plastic components if it remains on them 
too long. 

If the capstan flywheel appears slug- 
gish, remove it and clean it with alcohol. 
Also clean around the flywheel-bearing 
area using a cleaning stick dipped in alco- 
hol. Place a drop of oil upon the capstan 
bearing and replace the capstan. Wipe off 
any excess oil with a paper towel or cloth. 
Clean the capstan-drive area well to re- 
move any remaining oil. 

A dry capstan-bearing may be respons- 
ible for erratic or slow tape motion, and 
noisy and squeaky sounds may be caused 
by dry motor or pulley bearings. Excess 
oxide on the pinch roller can also be the 
cause of slow speed or tape pulling. Oil 
on any drive surface may produce slow — 
or no— motion in the parts it contacts. 



Erratic bunching of tape from the cassette 
may be caused by a drop of oil on the 
drive surface of the take-up turntable. 

All rubber or plastic drive-pulley sur- 
faces should be cleaned with a cleaning 
stick, and a drop of light oil placed on the 
pulley bearings. Any excess oil should be 
wiped off. All sliding parts should receive 
a thin coat of light grease. Finally, most 
motors have sealed bearings and never 
needed lubricating. 

After cleanup and lubrication, it's al- 
ways a good idea to demagnetize the re- 
cord/playback head to insure best fre- 
quency-response, and then to check the 
unit out to sec how it performs. 

Now we'll discuss some commonly en- 
countered problems, and their causes and 
remedies. 

No play or fast-forward 

When the recorder's in the play or 
record mode, the capstan and pinch rol- 
ler pull the tape across the record/ 
playback head, with the takeup turntable 
causing the tape to be wound on the cas- 



sette's takeup hub. In fast forward, the 
tape moves in the same direction, but the 
takeup turntable runs at a faster rate of 
speed; the capstan and pinch roller are 
disengaged. It's possible for one de- 
fective component to affect all of those 
functions. 

If the capstan or tape will not move 
with the play switch engaged, check for 
a defective on/off switch. Hold the unit 
close to your ear and see if you can hear 
the motor running. If the motor is dead, 
check the power switch and see whether 
the voltage is being applied to the motor. 
If the motor is operating, check for a loose 
or broken drive belt. If the unit works on 
AC, but not from its batteries, make sure 
that batteries are not weak or dead. 

Erratic fast-forward action can be 
caused by a dirty, worn, or binding turnt- 
able. Check for oil on the idler wheel or 
drive pulley (see Fig. 2). 

Sometimes the fast-forward lever may 
bend and not permit the drive pulley to 




FIG. 2— FAST-FORWARD probiems may be 
caused by oil on the Idler pulley or capstan/ 
flywheel. 



engage the capstan. Check for a weak 
spring or an out-of-position lever mech- 
anism, A good cleanup of the take-up 
turntable and a drop of oil on the drive 
pulley bearing may cure erratic fast- 
forward motion. 

No rewind 

If a recorder/player operates normally 
in the play and fast forward modes, 
but not in rewind, suspect that the idler 
or drive pulley is not engaging the supply 
turntable. In some units the idler pulley 
gets shifted to the left and rotates the 
supply spindle in the opposite direction. 
A dry or worn supply turntable may be the 
cause of erratic rewind, as well as of slow 
speeds. 

To remedy erratic rewind, remove the 
supply turntable and clean it with a cloth 
dampened with alcohol. Don't forget to 
dry it off afterwards. Place a drop of light 
oil on the turntable bearing, and then re- 
place the turntable. Clean the rubber or 
plastic drive area with alcohol and use a 



GO 

g 

2 

o 



UJ 

Q 
< 



cleaning stick to clean off the idler or 
drive-pulley surface area. Also check for 
a worn or binding idler-pulley. 

If a loud chattering noise is heard when 
the cassette is almost rewound, suspect 
dry hub areas in the cassette itself. A tiny 
drop of oil in the plastic hub area may 
help, but be careful; you don't want to 
ruin the tape. 

Slow speed and wow 

Slow-speed problems may be caused 
by a dry-capstan-bearing or by oil on the 
drive surface. A dry or wom pinch roller 
can also be responsible for slow speeds or 
wow. Replace the pinch roller if you find 
it's out of round after cleanup. (A de- 
fective pinch roller can also cause the tape 
to ride high or to pull from the cassette.) 

Check for a loose drive belt, or oil on it, 
when wow or slow -speed symptoms are 
noted. You may find that the motor belt 
slips right at the drive-motor pulley. 
Some of the important points to check are 
shown in Fig, 3. 

Also, look for a black area or small 
particle of rubber on the motor pulley; 
those signs indicate that the belt is slip- 
ping. Since the belts are very small in 
diameter and stretch easily, it's best to use 
an exact belt replacement. Finally, don't 
overlook the possibility of a defective 
cassette being responsible for wow. 

Check the motor 

A defective motor can cause slow 
speed and wow conditions. Generally, a 
defective motor will start at normal 
speed, and then slow down. Sometimes if 
you tap the motor housing, it will speed up 
again. In most units you will find a motor- 
speed potentiometer that can be used to 
adjust the speed over a certain range. If 
the speed adjustment has no effect, check 
the speed-control circuit and motor. (A 
typical circuit is shown in Fig. 4.) 

In some cases you may find that the 
motor is running too fast. Adjust the 
speed control, using a piano or music 
selection as a reference. You can also use 
a frequency counter to determine the cor- 
rect speed. 

If the motor is still running too fast, see 
whether the belt is riding too high on the 
motor pulley. If none of the above adjust- 
ments help, install a new motor, using an 
exact replacement. 

Pulling and bunching tape 

Bunching and unraveling of tape in a 
cassette player may be caused by an erra- 
tic or inoperative take-up turntable. The 
take-up turntable or spindle winds the 
tape coming from the capstan into the 
cassette. When the take-up spindle be- 
comes dirty or starts to bind, the excess 
tape will bunch up and pull out of the 
cassette. Remove the take-up turntable 
and clean it with alcohol. Apply a drop of 
oil to the bearing area. Also, clean the 
turntable -drive area. Check the idler and 




FIG. 3 — CHECK THESE AREAS it you are experiencing slow-speed or wow problems. 



SV 

DC 



R 101 
560fi 



TR21 
2SB3Z4 



R 102 
UK 



-TRIOS <R 



i 



TR22 
2SC8ZB 



Q> 



-w — +t- 




1 " 

tLc!01 <R104 

I3.3j.F >2im 
1 1 1 



C102 
•02 



filQS 
.5fi 



R106 
1.8K 



SPEED 
V R 10 1 

soon 



R107 
3.3 K 



© 



MOTOR 






FIG. 4— MOTOR-SPEED CONTROL circuit used by J.C. Penny model 6541. Circuits in other 
recorders should be similar. 



drive pulleys for oil or dirty drive- 
surfaces. 

Sometimes the pressure roller may be- 
come worn or out of round, and cause the 
tape to ride high and pull out of its proper 
path. In that case, try cleaning the pinch 
roller and capstan with alcohol. A bent 
capstan may also cause tape pulling. 

If the take-up turntable, pinch roller, 
and capstan appear to be normal and the 
player is still pulling tape, check the take- 
up torque with a torque gauge. Finally, 
remember that a defective cassette can 
cause tape to unravel or bunch up. 

No sound 

If the tape is moving but there's no 



sound, suspect the record/playback head 
or the amplifier section. Quickly rotate 
the volume control up and down and lis- 
ten for a scratchy sound from the speaker. 
If you can hear some noise, it's an indica- 
tion that the amplifier is working, so sus- 
pect the record/playback head. If you hear 
a loud hum with the volume wide open, 
check for a broken wire at the record/ 
playback head. Since the head assembly 
moves forward every time the play or 
record buttons are pushed, the wires 
leading to it have a tendency to break with 
time. 

To determine whether the record/ 
playback head is defective, pass a small 
screwdriver-blade rapidly across the head 



ea 



area. You should hear a flutter from the 
speaker. If you don't, dismantle the play- 
er fay removing both the top and bottom 
covers. Check the head connections for 
broken wires. Touch the screwdriver 
blade to the ungrounded side of the tape 
head. With volume wide open you should 
hear a loud hum; a loud noise would indi- 
cate that the tape head may be defective. 
Remove the cable-leads and measure the 
resistance of the head. Normally, that re- 
sistance will be between 50 and 800 
ohms. 

Defective components in the audio 
stages can be located with an audio- 
generator/signal tracer and through vol- 
tage measurements. Start at the first AF 
transistor and inject a 1-kHz signal to the 
base of each transistor. Step by step, 
check each stage. When the signal 
appears, you have located the defective 
stage. Check each transistor in the prob- 
lem area for out-of-line voltages. (A 
schematic is a must when servicing cas- 
sette-recorder amplifier circuits.) 

In some earlier units you may find five 
or more small transistors in the amplifier 
stages, while in present-day ones only 
one or two transistors may precede a 
power- IC output circuit. Such a circuit is 
shown in Fig. 5. To signal -trace the IC 
circuits, inject an audio signal at the IC's 
input pin and use the speaker as the in- 
dicator. To make sure the IC really is 
defective, measure the voltages at each 
pin. With correct voltages, but no signal 
from the IC, you can safely assume that 
the IC is defective. If the IC is leaky, even 
the supply voltage may be affected. 

Weak and distorted sound 

Weak and distorted sound may be 
caused by a dirty record/playback head. 
Clean the head with alcohol and a clean- 
ing stick, as described earlier, before tear- 
ing into the amplifier. A weak battery or 
insufficient operating voltage can also 
affect the quality of the sound. 

FHOM 
Ql 



+ J_CB 
~ IMF 




FIG. 6— RECORD OSCILLATOR CIRCUIT used by Sharp model RD-428UA. Use a scope on LI to 
determine whether the oscillator is working. 



The best method for locating a weak 
audio-stage is to inject an audio signal, 
with a scope connected to the output of 
the recorder/player so that you can 
observe the audio waveform. Start at the 
record/ play-head connections. The signal 
should be the same on both sides of the 
electrolytic coupling-capacitor. (Most 
weak-sound problems are caused by 
small coupling-capacitors and transistors 
in the amplifier section.) If it is not, shunt 
a new capacitor across the suspected one 
and see whether the sound returns. Each 
transistor in the amplifier section should 
have a large gain from its base to collector 
terminals. 

Excessive distortion may accompany a 
weak-signal condition. Most distortion in 
small amplifiers takes place in the output 
stages. In push-pull transistor output- 
circuits, an open or leaky transistor can 
produce weak and distorted sound. Since 
most circuits of that type are DC-coupled, 
check the driver or AF transistor for in- 
correct bias on the output transistors. 



VOLUME 



VRl 
EOK 

PIN: 

• 1 

4 
5 
6 
8 
9 

10 

12 

13 

14 



SI -4 



C3 



-Jh- 



C1D ^. 

.001' 



TEST VOLTAGE 
2.S3 
4.22 
0.79 
2.85 
1.12 
2.25 
3 

s.ai 

5.89 
5.97 



-Wr- 







FIG. 5— IC OUTPUT CIRCUIT used in Sanyo model M100O. Voltages shown are typical for this 
unit but may be different in others. 



Remove both transistors when distor- 
tion is located in a push-pull output cir- 
cuit — it's best to check each transistor for 
leakage out-of-circuit. Before replacing 
the output transistors, check the emitter 
and bias resistors for correct values. 
Generally, a burnt emitter- resistor will be 
found along with a shorted or leaky out- 
put-transistor. 

A leaky IC can also produce weak and 
distorted audio. Replace the suspected IC 
when no signal will pass through it or if 
incorrect voltages are measured at its 
pins. Use a wick-type solder absorber 
(like Solder-Wik) to remove the excessive 
solder from the IC pins to make removing 
the part easy. Then use a low-wattage 
pencil iron to install the new IC. 

No record function 

If the unit will play but not record, 
suspect a dirty play/ record switch or 
defective record circuits. First, make sure 
the record/playback head is clean. Then 
spray the play/record switch with con- 
tact-cleaner. Work the switch back and 
forth to clean the contacts and then try to 
record once again. 

Although most portable recorders do 
not have an oscillator stage to excite the 
record tape-head, you may run across one 
that does. A representative circuit is 
shown in Fig. 6. To determine whether 
the oscillator is operating, use the scope 
and check the waveforms at the prim 317 
and secondary windings of LI . Transistor 
testing of Q2 and voltage measurements 
can indicate whether the transistor is 
functioning properly. 

Check for poor connections to the 
built-in microphone. Most built-in mikes 
are electret-capacitor types and require a 
DC -volt age to work, so test for that vol- 
tage at one of the microphone terminals. 
A defective microphone may be respons- 
ible for weak or erratic recordings. Sub- 
stitute a dynamic microphone across the 
shielded wires to the built-in mike ter- 
minals (but do not connect it to the DC 



(Si 



CD 

m 

3D 
(O 

ro 
69 



o 

z 

o 
rr 

LU 
LU 

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source). If the built-in microphone proves 
to be defective, exchange it for an exact 
replacement. 

Adjustments 

When ' 'crosstalk' ' or poor playback is 
noticed, check the erase head, and the 
azimuth adjustment of the record/ 
playback head, A defective erase head 
may allow previously-recorded material 
to remain on a tape, producing a garbled 
mess when new material is recorded. 
Most erase heads found in portable rec- 
orders are DC-operated. Check for a DC 
voltage across the erase head with the unit 
in the record mode. Also check the re- 
sistance of the erase head in case there's 
an open internal winding. 

The only adjustment on a portable rec- 
order's record/playback head is for azi- 
muth (elevation). The azimuth- 
adjustment screw is usually located on 
one side of the head, with a coiled spring 
underneath it. Connect a VTVM with an 
eight-ohm dummy load to the earphone 
jack. Insert a 3-kHz or 6.3-kHz test tape 
and start it playing. Adjust the azimuth 
screw for the highest reading on the 
VTVM. After that has been done, you 
may want to dab the adjustment screw 
with paint or glue to secure it in place. 

The only other mechanical adjustments 
are for take-up torque and adjustment of 
the pressure roller. (You may find that 
either one or both adjustments are fixed in 
some models.) The pressure-roller 
adjustment can be made using a spring 
scale and changing the position of the 
pressure-roller spring to vary the tension 
it puts on the mechanism. 

Take-up torque should be measured on 
the take-up turntable with a torque gauge 
while in playback mode. Most take-up 
torque readings should be between 35-60 
gr-cm. For greater tension, bend the ten- 
sion spring and, if necessary, replace the 
take-up pulley. It's best to follow the 
manufacturer's service literature for cor- 
rect tension adjustment. 

Now let's take a look at some typical 
case histories. 

Weak and distorted output 

A GE NBR-353IJC had weak and 
distorted sound. Although the symp- 
toms indicated possible output- transistor 
problems, the tape head, pinch roller, and 
capstan were cleaned with alcohoi as a 
matter of routine. The weak condition 
still remained, as expected. 

When the back cover was removed we 
noticed that new batteries had been in- 
stalled. Only 2. 7- volts was measured at 
the adjustment transistors. Either the 
transistors were defective or something in 
the circuit was loading down the voltage 
source. A bench supply was connected to 
the player for servicing and everything 
worked normally. It turns out that one of 
the new batteries was practically dead, 
and the battery terminals were corroded. 
A good cleanup of the battery terminals 




FIG. 7— THe UNINSULATED swltoh lever shorted out the power-supply voltage in this Sharp model 

RD-428UA. 

and a set of fresh batteries solved the 
weak -audio/distortion condition. 

No play, no record 

In a Sharp RD-428UA, we found that 
the motor was turning, but we couldn't 
play or record. Both rewind and fast 
forward modes were normal. When 
both covers were removed, we found that 
the motor did not run in either the play or 
record modes, and the sound would cut 
out with the volume control wide open. 

The "no play, no record" symptom 
turned out to be an electromechanical 
problem (see Fig. 7). When the record/ 
play switch's metal plunger touched one 
of the switch's leaf contacts, which pro- 
vided power to the motor and amplifier 
circuits, the voltage source was shorted 
out. It seems that the small rubber insulat- 
ing sleeve was missing from the switch 
lever. The problem was solved by epoxy- 
ing a piece of large "spaghetti" over the 
lever. 

Squeaky playback 

After about five minutes of playback, a 
Sharp RD-428 would develop a squeak- 
ing noise. The noise would only occur in 
die play mode, and only when the wheel 
or pulley came around to a certain posi- 
tion. Sometimes by probing around with 




FIG. 8— DRY IDLER PULLEY was cause Of 
squeak in this recorder. It's a good idea to 
remove the problem parts for cleaning and 
lubrication. 

an insulated tool you can slow down the 
suspected pulley, thus eliminating the 
squeaky noise. 

In this particular model we found a dry 
idler-wheel bearing, as shown in Fig. 8. 
The spindle and turntables were re- 
moved, cleaned, and lubricated. A drop 
of oil on the idler wheel eliminated the 
squeaking noise. 

continued on page J 07 



70 




mmm 



73 




ALL ABOUT IM- 
PULSE GENERATORS 

This month we'll look at another pulse-generator application, testing analog circuits, as well 
as some problems that you might run into when you use that device. 



Part 4 



SO FAR WE HAVE CON- 

fmcd our discussion to 
using the pulse generator in logic-circuit 
analysis. While that is one of the prime 
functions of the pulse generator, it is not 
its only one. Let's begin this month by 
looking at another area where the pulse 
generator is useful — testing and analyz- 
ing analog circuitry. 

Analog circuits 

Using a pulse generator as a signal 
source can simplify many of the measure- 
ments that are often made when testing 
analog circuits. That's because, generally 
speaking, pulse generators are useful 
over a very wide frequency range, which 
can come in handy when working with 
broadband amplifiers, etc. 

For instance, a single, conventional, 
pulse generator is the only signal source 
you need to test an amplifier whose fre- 
quency response extends from below 1 
Hz to considerably more than 10 MHz. 
Otherwise, testing that amplifier would 
require using an audio generator for the 
low end and an RF generator for the upper 
end, or perhaps a very wide-range func- 
tion generator. 

The reason for that becomes apparent if 
the nature of a pulse is analyzed. Such 
analysis would reveal that the pulse's fast 
rise and fall times are caused by the 
pulse's high-frequency components, 
while the interval between the rise and fall 
times (i.e. the top of the pulse) is caused 
by the low-frequency components; in 
some cases, the frequency of those com- 
ponents is so low that it is approaching 
DC. Those high- and low-frequency 
components are what gives the pulse 
generator its wide frequency range. 

Frequency-response measurements on 

an amplifier are usually made at the 3-dB 

points; that is, the point at which ampli- 

I fier delivers half its rated power output, or 



CHARLES GILMORE 



70 percent of its rated voltage output. 
That 3-dB point is considered the upper 
and lower cutoff frequency of an ampli- 
fier. The simplest method to measure the 
low-frequency 3-dB cutoff is by adjusting 
the pulse generator so that the pulse droop 
is 25 percent. Pulse droop (the difference 
between the amplitude immediately 
following the leading edge and the ampli- 
tude at which the trailing edge begins) is 
expressed as a percentage of the ampli- 
tude at the leading edge (see Fig. 1 1). 

When the pulse droop is adjusted to 25 
percent, the width of the pulse is related to 
the frequency (in Hz) of the lower 3-dB 
point through the formula: 

t 

where t is the width of the pulse. The 
constant (0.0456) is derived from a 
Fourier analysis of the pulse. 

To measure the frequency of the upper 
3-dB cutoff, the following formula is 
used: 



L 



0.35 



where f B „p<, r is the upper 3-dB cutoff fre- 
quency (MHz), and t r is the pulse risetime 
in nanoseconds. 

While that formula has been idealized 
and is for a circuit where the product of 
the capacitance and inductance is 0, the 
formula will hold until that product ex- 
ceeds 0.25. After that point, some over- 
shoot begins to occur at the end of the 
leading edge, lowering the value of the 
constant, 0.35, in the formula. With over- 
shoot of 25 percent, for instance, that 
constant would be lowered to 0.28. 

Some additional information about the 
frequency response of a broadband 
amplifier can be obtained using a pulse 
generator. Remember that a pulse con- 




%Dfl00P: 



;■ mo::. 



LOWER 3dB CUTOFF 
, . 0.04 SS 

'-3dB ~ t 



FIG. 11— PULSE DROOP is useful in finding 
the lower 3-dB point of an amplifier. 



sists of a fundamental frequency plus a 
great number of even and odd harmonic 
components with specific phase rela- 
tionships with each other, as well as with 
the fundamental frequency. If that phase 
relationship is not maintained, the 
waveshape of the pulse deteriorates. If an 
essentially stable pulse waveform is 
passed through an amplifier, the amplifi- 
er's output can be examined for any 
aberrations in that waveform. The pres- 
ence of those aberrations indicates that 
the phase response of the amplifer is not 
uniform — i.e. , that there are peaks and/or 
valleys in the amplifier's frequency- 
response curve. That would be caused by 
either leading or lagging reactive ele- 
ments in the circuit. At that point, further 
analysis with a sweep generator or a low- 
distortion audio oscillscope is needed. 

As noted earlier, rise-time measure- 
ments let you determine approximately 
the upper frequency-response limits of a 
broadband amplifier. A few precautions 
must be taken when making such rise- 
time measurements. One thing that must 
be considered is the effect of the test 
setup. Each part of that setup plays a role 
in determining the rise time of the output 
that is displayed; in other words, the rise 
time of the pulse is changed slightly as it 
passes through the various parts of the test 
setup. The displayed rise time, therefore, 
is actually a function of the rise times 



m 

H 

m 
5. 
co 

m 

33 



71 



through each part of that setup and can be 
found from: 



o 
o 



UJ 

Q 

Q 
< 

tr 

72 



T R = 1.1 ,' T e 2 + V +T P 2 + T 2 

where T R is the display rise time, T fi is the 
rise time of the pulse generator, T A is the 
rise time of the amplifier under test, T P is 
the rise time of the probe, and T is the 
rise time of the oscilloscope. 

Because of its exceedingly fast rise 
time, a pulse generator is extremely con- 
venient for measuring propagation delay 
and phase delay. Both analog and digital 
circuits introduce some fixed time delay 
to signals that pass through them. For 
example, if a J-K flip-flop is clocked, it 
will take several nanoseconds for the re- 
sults of that clocking to appear at the 
output of the flip-flop. That delay in re- 
sponse is called the propagation delay of 
the flip-flop. 

Analog amplifiers also suffer from pro- 
pagation delay. The easiest way to meas- 
ure that delay is to use a dual-trace 
oscilloscope and a pulse generator. The 
pulse-generator output is applied to the 
amplifier's input and to one oscilloscope 
channel. The amplifier output is the ap- 
plied to the second channel of the oscillo- 
scope, and a comparison is made. 

If a dual-trace oscilloscope is not avail- 
able, you can use a pulse generator with a 
pulse-delay capability. In that case, the 
input to the amplifier is connected to the 
delayed generator output. The amplifier 
output and the non-delayed pulse- 
generator output are both applied to the 
oscilloscope. The pulse -del ay control of 
the generator is then adjusted until a sing- 
le pulse is obtained. The amount of delay 
neccessary to display the single pulse is 
equal to the propagation delay of the 
amplifier. 

In order to successfully combine the 
amplifier output with the pulse-generator 
output, some series-limiting resistance 
must be used. Great care must be taken to 
insure that the added circuitry does not 
contribute additional phase shift. Figure 
12 shows an example of such a situation. 

Pulse generators arc also useful in 
evaluating the high-frequency eharateris- 
tics of diodes and transistors. The diodes 
used in either radio- frequency or digital 
applications are required to recover very 
rapidly from switches between reverse- 
and forward -bias. 

When a diode is forward -biased, the 
area at the junction is filled with majority 
carriers. ("Majority carrier" is a term 
used in semiconductor electronics to de- 
scribe the predominant type of earner in a 
semiconductor material, In n-type mate- 
rial, the predominant carrier is the elec- 
tron; in p-type material it is the absence of 
an electron, which is called a hole.) When 
the diode is reverse-biased, the junction 
has few majority carriers. Obviously, the 
change in the number of majority carriers 
at the junction can not occur in- 
stantaneously. 



PULSE GENERATOR 



& « a 



UNQELAYED 



PULSE 




DELAYED 



PULSE 



> 






/k 



SCOPE 



J\ 



INSUFFICIENT PROPER EXCESSIVE 

GENERATOR GENERATOR GENERATOR 

DELAY DELAY DELAY 

FIG. 12— A PULSE GENERATOR is used here 
to measure the propagation delay through an 
amplifier. 



PULSE GENERATOR 



d 0UT 



= 50f2 



SCOPE 



6 © © 



J 1 0OnS |_ 




am 



rx: 



FORWARD RECOVERY 
VOLTAGE 



^FORWARD RECOVERY TIME 

FIG. 13— MEASURING THE FORWARD 
recovery voltage and forward recovery time 
of a switching diode. The pulse generator 
should be set for a 100-nanosecond pulse 
width with a less than 1 percent duty cycle. 
The output voltage of the generator should 
be set to produce a specified steady-state 
current in the diode. 



Let's first look at what happens when a 
diode is suddenly switched from reverse- 
to forward-bias. When that happens, the 
majority carriers move to the area around 
the junction. But, until that area is filled 
with those majority carriers, the voltage 
across the diode is considerably greater 
than its normal forward-biased voltage. 
That voltage transient is of concern if the 
diode is to be used in switching applica- 
tions. Figure 13 shows a test setup that 
can be used to measure that transient, as 
well as the waveform that would be dis- 
played on the scope. The size and dura- 
tion of the transient can be found by in- 
specting the waveform as shown. 

The forward-recovery specifications of 
a diode are normally given for some 
steady forward-current value, once the 
transient conditions have subsided. It is 
that forward current, combined with a 
50-ohm resistor, that determines the 
pulse generator's output voltage; pulse 
duration should be 100 nanoseconds. A 
generator having a 10- to 20-nanosecond 
rise time is suitable for that test, and no 
offset voltage is required. 

Now, let's consider what happens 
when a diode is suddenly re verse- biased. 



When that happens, a large reverse cur- 
rent flows until there are few majority 
carriers left around the junction. How 
long that current flows is important if a 
diode is to be used in a switching applica- 
tion. Figure 14 shows the test setup used 
to measure that, as well as the waveform 
that is likely to be seen on the scope. 

The requirements placed on the pulse 
generator and the oscilloscope used to 
measure reverse-recovery time are some- 
what greater than those for forward- 
recovery time. Re verse- recovery time in 
diodes is on the order of a few 
nanoseconds, and the rise time of the 
pulse generator must be considerably 
less. In many cases, the rise time of both 
the pulse generator and the scope must be 
less than 1 nanosecond. However, gener- 
ators with more moderate specifications 
can be used to test slower diodes. 

Figure 1 5 shows the test setup used to 
measure the turn -on and turn-off times of 
a switching transistor, as well as the 
typical waveforms that would be dis- 
played on the scope. That test is one of the 
most important ones done when you are 
analyzing the operation of a switching 
transistor. 

As with a diode, transistor specifica- 
tions are given at some specified base- 
and col lector- current levels . The bias and 
B+ voltages supplied to the circuit es- 
tablish proper transistor operation and 
should be selected so that those currents 
are at the proper level. Note that turn-on 
time is determined by noting the point 
where the generator's output rises to 10 
percent of its final value and the point 
where the transistor's output drops to 90 
percent of its initial value. Conversely, 
turn-off time is measured between the 
points where the generator's output drops 
10 percent from its maximum level, and 
the transistor's output rises to 90 percent 
of its initial value. Once again, for tran- 
sistors with reasonable switching speeds, 
the pulse generator and the oscilloscope 
must have relatively good rise-time speci- 
fications. However, pulse generators 
with more moderate capabilities can be 
used to perform those tests on some slow- 
er transistors. Other transistor measure- 
ments that can be made include storage 
time, stage rise time, and voltage break- 
downs. 

Using a pulse generator when testing 
transistors and diodes has several advan- 
tages. Two of the most obvious are that 
they can be used to supply a bias offset 
voltage, (eliminating additional power 
supplies) and that their sharp rise times 
eliminate the need to measure the rise 
time of the generator itself. In addition, 
pulse generators can be operated at ex- 
tremely low duty cycles. For instance, in 
the diode and transistor tests we just dis- 
cussed, duty cycles of one percent or less 
are called for. Such low duty cycles let 
you perform tests that could not be safely 
done under steady-state conditions. Such 
steady-state testing would overheat many 



of the devices, possibly destroying them, 
or at least changing their electronic char- 
acteristics. Even though peak power de- 
veloped in a circuit when using a pulse 
generator may far exceed the maximum 
permissible continuous power, with that 
device's low duty-cycle the average pow- 
er is well within its ratings. 

Sources of error 

A pulse generator is probably one of 
the easiest instruments to use improperly. 
The vast number of settings and modes 
make it easy to set up improperly. There- 
fore, using a pulse generator without an 
oscilloscope is not advisable. With a 
scope, you can easily spot setup errors 
and correct them. 

The most frequent errors in using a 
pulse generator are human errors. For ex- 
ample, a common mistake is exceeding 
the allowable duty cycle. As noted ear- 
lier, a 70 percent duty cycle is common 
for most pulse generators. The most usual 
mistake here, however, does not involve 
exceeding the duty cycle by a small 
amount (such as 75 percent as opposed to 
70 percent, for example), but by exceed- 
ing it by orders of magnitude. That hap- 
pens when, for instance, a pulse- 
repetition rate of 1 kHz has been es- 
tablished, but a pulse width of 10 mil- 
liseconds is chosen instead of 10 mic- 
roseconds. In that situation, the duty cy- 
cle has been exceeded by a factor of 10. 
On pulse generators with a pulse -de lay 
feature, a similar error occurs. In that 
case, the delay time exceeds the time es- 
tablished by the pulse-repetition rate. A 
pulse generator set for a repetition rate of 
1 pulse-per-millisecond might have the 
delay generator set at 10 milliseconds. 
Due to the nature of the monostable multi- 
vibrator used to generate the delay time, 
the first pulse is chosen to generate the 
10-mi Hi second delay interval, and the 
following nine pulses are ignored. The 
result is one pulse- per- 10 milliseconds, 
even though the pulse-repetition rate has 
been set for 1 pulse-per-millisecond. 

Variable rise- and fall-times, although 
a useful feature, can also give rise to 
errors. For instance, assume a pulse width 
of 20 nanoseconds is desired. If, howev- 
er, the rise- and fall-times are set at 15 
nanoseconds, the time required to reach 
the maximum output and drop back to 
zero would be a total of 30 nanoseconds, 
10 nanoseconds greater than the pulse 
width. Thus, the pulse does not have 
enough time to reach the proper levels, 
making any measures of amplitude in- 
correct. 

As noted previously, improper 
transmission lines or terminations can 
seriously degrade pulse characteristics. 
Care must be taken to prevent pulses that 
are distorted beyond recognition. 

In similar fashion, certain situations 
require the pulse to be split between two 
different transmission lines and later re- 



combined by some form of circuity. If 
narrow pulses at a high rate, and relative- 
ly long cables are used, great care must to 
taken to insure that both pulses arrive at 
the proper termination simultaneously. If 
that is not done, pulse-stretching may 
occur. 

In many cases, both the amplitude and 
the offset controls of the pulse generator 
have extremely coarse calibration; that 
can cause misadjustment. Errors can easi- 
ly occur when setting the generator's out- 
put amplitude. A 50 percent setting, for 
instance, does not mean 50 percent of the 
rated amplitude. The output specification 
of the generator indicates a maximum 
output, but that output is usually given in 
terms of "not less than." In many cases, 
the actual output can exceed that rated 
output by as much as 20 to 25 percent. As 



PULSE GENERATOR 

z OUT = 5on 



SCOPE 







■ov PULSE 
FROM 



GENERATOR 



~UL 



-REVERSE RECOVERY TIME 



FIG. 14— MEASURING DIODE reverse- 
recovery time. A 100-nano second pulse- 
width with a duty cycle of less than 1 percent 
should be used. The generator rise time 
should be less than the expected reverse- 
recovery ti me. Th e pos iti ve p u Ise off set i s s et 
to generate the specified forward current. 
A 60-ohm resistor converts the output cur- 
rent to voltage for display on the oscillo- 
scope. 



PULSEGENERATOR 

ZoLT=6on 



SCOPE 




FIG. 15— MEASURING THE SWITCHING time 
of a transistor. The pulse generator is set for 
a 100-nanosecond pulse-width with a duty 
cycle of less than one percent. 



a result, the most accurate way to set the 
output amplitude is to monitor the gener- 
ator's output on a scope. Another possible 
error in setting the output amplitude can 
be introduced by using an output atte- 
nuator. Those errors are caused by using 
the wrong level of attenuation and are 
quite large — at least one order of magni- 
tude. 

Generator-induced errors 

A pulse generator is usually not cali- 
brated very precisely. However, if you 
are fully aware of all its specifications and 
what they mean, you will have little or no 
problem in getting maximum use from the 
instrument. However, failure to recog- 
nize some of these specifications can re- 
sult in generator- induced measurement 
errors. Jitter can occur in the repetition 
rate, the amount of pulse delay, and the 
pulse width. The amount of jitter must be 
taken into consideration when a rather 
stable pulse-width, delay, or repetition- 
rate is required. 

When using a pulse generator, es- 
pecially over extended periods of time, it 
is necessary to reset the operating 
parameters, many of which can vary over 
time, or with changes in temperature and 
other factors. Certain pulse-generator 
characteristics are affected by changes in 
the load (for example, the baseline offset, 
which is often simply a current generator 
operating into a known load). 

Frequently, certain pulse-generator 
controls interact somewhat. For example, 
any changes in the rise time and fall time 
of the output pulse can cause changes in 
the pulse width and amplitude. 

When you use the dual-pulse or twin- 
pulse mode, make sure that the delay time 
is long enough to permit the first pulse to 
return to zero before the second pulse is 
generated. It is possible to set two pulses 
with such a short delay time between 
them that they never return to the base- 
line. 

Finally, it is important to remember 
that the best way to get the most out of a 
pulse generator is to use it with a good 
oscilloscope. R-E 




^ j-^ lcnve ll 



"I'd like to turri it off, father, but he's 
telling me to stay tuned, and he's bigger 
than you.'" 



m 



m 

tu 
m 
J> 

to 
co 
w 

73 



HOBBYCORNER 



Learning about microprocessors 

EARL "DOC" SAVAGE K4SDS, HOBBY EDITOR 



s 

o 



a 
< 

74 



WHAT DO YOU KNOW ABOUT M1CRO- 

processors? If nothing else, I hope you 
know at least that a microprocessor is the 
"heart" or "brains" of a microcompu- 
ter. Actually, maybe "brains" is the 
wrong word to use, because a 
microcomputer is just as dumb as an 
electric motor, in spite of appearances to 
the contrary — but that's another story. 

You should certainly be aware that a 
microprocessor is not a microcomputer, 
and vice versa. You will find that, 
through carelessness or ignorance, those 
terms are used interchangeably on occa- 
sion. Do not be confused. A micropro- 
cessor is one small integrated circuit. A 
microcomputer is made up of a group of 
IC's that includes a microprocessor as the 
"controller of operations." The micro- 
processor, then, can be thought of as the 
foreman of a crew that, together con- 
stitutes a microcomputer. (We will ignore 
for now the so-called "single-chip com- 
puter.") 

Why should you be concerned about 
microprocessors since you have no inter- 
est in microcomputers? There are two 
good reasons. The first is that more and 
more, microcomputers are effecting ev- 
ery aspect of our lives; whether you like it 
or not, in all likelihood, you will, even- 
tually have to learn at least a little about 
them. 

The second reason is perhaps more im- 
portant. In the past, microprocessors 



aee.0 •switch 

(AT BELL CO(i-) 



IOOJ1 




I—" °~f f ♦— — T- 1 "*^ 1 



were found only in computers. Today, 
you can find them in microwave ovens, 
television and radio receivers, cars, 
games, and other devices. Before long, 
you will find them in everything except 
the simplest devices. 

If you don't learn what micropro- 
cessors are, how they function, and what 
they can and can't do, you are going to be 
left out of the most interesting de- 
velopments in electronics. You won't 
even be able to fix many of the electrical 
things around the house. Your hobby ac- 
tivities will become outdated. 

Consider the plight of those who know 
how to work with tubes but arc lost with 
transistors. (I, too, was once in that boat.) 
Others know trnasistors but never have 
gotten the hang of IC's. 

When those hobbists write, invariably 
they want to know how and where to get 
started in catching up. I hope you won't 
let progress pass you by too. Micropro- 
cessors are here and they are already be- 
coming common in many applications. 

Make no mistake — in spite of anything 
you may have heard ot the contrary, a 
microprocessor is not just another "run- 
of-the-mill" IC. They are complex little 
devils that can be made to do some re- 
markable things. Yet, they are not all that 
difficult to work with and understand if 
you tackle them in an organized, logcial 
manner. 

One of the most thorough in-depth 



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treatments of microprocessors that I have 
found is published by the McGraw-Hill 
Book Company, Gregg Division, (1221 
Avenue of the Americas, New York, NY 
10020). Introduction To Micropro- 
cessors, by Charles M. Gilmore, is a 
textbook that can be used in a classroom 
or for independent study. The treatment 
of the material is quite thorough and, in 
one way at least, unique. 

That text is not about the Z80, 6809. 
8085, 1802, or any of the other available 
microprocessors. It is, in fact, about an 
imaginary microprocessor. Because of 
that, you leam about microprocessors in 
general and not just a specific one. It is a 
relatively easy matter to apply what 
you've learned to any microprocessor 
you work with later. Do not mis- 
understand — this book is not simply an 
introduction to microprocessors; the au- 
thor gets right down to the nitty-gritty of 
the subject. 

Don't get caught having to play catch- 
up later- — do yourself a favor and find out 
about microprocessors now. 

Flashing-light "doorbell" 

Tom Haase of Oklahoma City sent the 
schematic shown in Fig. 1. That is his 
simple answer to a request we ran asking 
for a way to let deaf persons know the 
doorbell is ringing. 

As indicated, the reed switch is placed 
very close to the coil in the doorbell or 
buzzer. The magnetic field of the coil 
causes the switch to close, activating the 
555 one-shot. That, in turn, starts the 
3909 LED flasher, which pulses the relay 
and flashes the light, 

Tom has installed three of those de- 
vices for friends who are deaf. Tom also 
suggests that a strobe light could be used 
by omitting the 3909 flasher. 

Thanks, Tom, for a neat solution to a 
serious problem. 

A shocking project 

I got a nice letter from a fellow in 
Australia the other day. He asked for 
some help on a project. At least that was 
his intention, but he was really asking me 
to help get him in trouble. 

My Australian friend wanted to hot- 
wire his car with a "shocker" to keep 
vandals away from it. Well, it is possible 
to shock a person without killing him but 
who is to say who might touch the car? 



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pp (EIA RS-17Q|i . . . EDITING FEATURES: insert/delete line, insemdelele character, for- 
wardrback tab . . LINE OR PAGE TRANSMIT . PAGE PRINT FUNCTION . CURSOR POSI- 
TIONING: up, down, rlght 4 left, plus absolute cursor positioning with read back . . . VISUAL 
ATTRIBUTES: underline, blink, reverse video, hall intensity. 5. blank . . . GRAPHICS: 12,000 
pt>;el resolution block plus line graphics . . , ON-SCREEN PAHITY INDICATOR . . . PARITY: off, 
even or odd . . . STOP BITS: 110 baud 2. all others 1 . . . CHAR. OUTPUT; 7 by 11 character In 
a 9 by 12 block , . . PRINTER OUTPUT ... 60 OR 50 Hi VERTICAL REFRESH . . . BLINKING 
BLOCK CURSOR . - . CRYSTAL CONTROLLED . . . 2K ON BOARD RAM . . ASCII ENCODED 
KEYBOARD: 56 key712B character . . . 4K ON BOARD ROM . . , COMPLETE WITH POWER 
SUPPLY. 

TELEPHONE MODEM tfjj OfA . FULL DUPLEX, FCC APPROVED , DATA RATE: 300 baud 
. , . INTERFACE: RS232/C and TTY . . . CONTROLS: talk/data switch (no need lo connect and 
disconnect phoney, originate! answer switch on rear panel . , NO POWER SUPPLY RE- 
QUIRED. 

ASCII KEYBOARD ASCIIS 58 KEYr128 CHARACTER ASCII 
EN CODED UPPER & LOWER CASE . . FULLY DEBOUNCED 
2 KEY ROLLOVER - POS OR MEG LOGIC WITH POS STR0SE 
REQUIRES f£l -12V DC (SUPPLIED FROM VIDEO BOARDS) 
PRINTER COMET I - . SERIAL 3K> TO 9600 BAUD , . . 80 
CHARACTER COLUMN (132 COMPRESSED) . . . 10" TRACTOR FEED 1 
. . . UPPER/LOWER CASE . . INDUSTRY STANDARD RIBBONS . . . 
4 CHARACTER SIZES - 9 BY 7 DOT MATRIX . , BIDIRECTIONAL 
PRINTING 

Continental USA. CredU Card Buyers Outside Connecticut 

CALL TOLL FREE 800-243-7428 

To Orde. From Connecticut Or For Tech. Assist. Call 1203) 354-9375 

NETRONICS R&D LTD. d. p i. 

333 Litchfield Road, New Miltord, CT 06776 

Ptesse send the items checked betovr. 

COMPLETE FASTEP.M-64 TERMINAL (includes FASTVtD-64 video board 
ASCII -3 Keyboard, steel cabinet and power supply) ... Kit $199.95 plus S3 P&l 
. . . wired & tested $249.95 plus $3 P&l . . . graphics option: add $19.95 to 

ddcfi of StiOvfi 

:. COMPLETE SMARTERM-BO TERMINAL(lncludes SMARTVID-80 video 
board. ASCII-3 keyboard, steel cabinet and power supply) ... kit $299.95 plus 
$3 P&l . . . wired and tested $369.95 plus $3 P&l 

□ FASTVID-64 VIDEO BOARD (requires +5 & -12V DC) . . . kit $99.95 plus $3 
P&l . . . graphics option add $19.95 ... wired & tested $129.95 plus S3 P&l . . . 
graphics option add S19.95 

□ SMARTVID-SO VIDEO BOARD (requires + 5 & + M2V DC) . . . kit $199.95 
plus $3 P&l . . . wired & tested $249.95 plus $3 P&l 

C DELUXE STEEL TERMINAL CABINET . , . $19.95 plus $3 P&l 

C ASCII-3 KEYBOARD (requires +5 & -12VDC) ... kit $69.95 plus S3 P&l . . . 

wired and tested $89.95 plus S3 P&l 

□ POWER SUPPLY (powers ASCII-3 keyboard & video boards) .kit only 
$19.95 plus 12 P&l 

□ ZENITH VIDEO MONITOR (high resolution green phosphor) . .. wired & 
tested S149.95 plus $6 P&l 

G TELEPHONE MODEM MODEL 103 Q;A wired & tested S1S9.95 plus $3 

P&l 

C DOT MATRIX PRINTER Gomel I . . . wired & tested $299.95 plus S10 P&l 

□ RF MODULATOR MOD RF-1 ... kit only $8.95 plus $1 P&l 

: : 3FT-25 LEAD MODEMfTERMINAL OR PRINTER/TERMINAL CONNECTOR 
CABLE . . . $14.95 ea plus $2 P&l 

For Canadian orders, double the postage . Conn. res. add sales tax. 

Total Enclosed $ 

□ Personal Check D Cashier's Check/Money Order 

□ VISA □ MasterCard (Bank No. ) 

Acct. No . Exp. Date 

Signature 

Print Name 

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CIRCLE 38 ON FREE INFORMATION CARD 



Someone with a weak heart could brush 
by it accidently and suffer a fatal shock. 

The letter reminded me of a guy who 
wired his garbage cans to raw AC "to 
keep the dogs out of them." That nut 
could have electrocuted someone. 

Be smart. Don't let your knowledge of 
electronics overcome good sense. I don't 
know about the laws in Australia, but I 
suspect that there, as well as here, a guy 
could get himself in serious trouble by 
pulling a stunt like that. 

Something for nothing 

Seldom, if ever, does one get some- 
thing for nothing. There is another scam 
going around that I'd like to warn you 
about; you should be on guard if it comes 
your way. 

You know, of course, about the illegal 
chain letters that promise riches. It seems 
that someone has come up with a new 
version. 

One of our readers from We Hand, 
Ontario, Canada sent me a "membership 
form" from a "Book Club," Most of the 
chain letters that I've seen ask for money, 
but this one asks for books and magazines 
instead. Interestingly, almost half of the 
names/addresses on the list are from Cen- 
tral America (the rest are from the U.S.). 
The reader thinks that they got his name 
and address from a letter published in a 
magazine, R-E 



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CIRCLE 39 ON FREE INFORMATION CARD 



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COMMUNICATIONS CORNER 



Touch-Tone devices and FM adjustments 

HERB FRIEDMAN, COMMUNICATIONS EDITOR 



AS MORE AND MORE COMMUNICATIONS 

systems requiring Touch-Tone signals for 
access and operation made their appear- 
ance, 1 found that the Touch-Tone pad I 
had purchased several years ago had be- 
come a constant companion. 

The pad was purchased from a Radio- 
Electronics advertiser and was either 
standard Bell System "surplus," or sal- 
vage from a Touch-Tone phone. 1 in- 
stalled it in a matching plastic case, for 
which I paid a couple of dollars (it's now 
selling for $10-$ 15), added a battery for 
power and a set of output-signal clip 
leads, and I carried it in my attache case or 
the glove compartment of my car. 

If I needed to access my 2-meter 
repeater's autopatch I plugged the pad 
into a small jack I had installed on my 
2-meter mobile rig. (That was before 1 got 
Heathkit's combination mobile mike and 
Touch-Tone pad.) To enter information 
into my computer from a remote point I 
clipped the leads from the pad across the 
phone line if I couldn't locate a Touch- 
Tone phone during my travels. 

Like just about all other Bell System 
equipment, the gadget has never failed. 
The only problem is that its frequencies 




CDn 



HF 

LOW PASS 
FILTER 



HI 



;kci 




FIG. 2 



FIG. 1 



are determined by pot coils (inductors) 
that are huge by contemporary standards. 
Until recently 1 was always lugging 
around some sort of case just to carry the 
pad. 

Though the earliest users of portable 
Touch-Tone pads were radio amateurs 
and other hobbyists, with the tremendous 
expansion in communications circuits 
and computers requiring Touch -Tone sig- 
nals for control or data, there has been 
created a need for a truly portable Touch- 
Tone generator that can be easily coupled 
to a standard telephone. One of the ear- 
liest — and still popular — devices was the 
Soft Touch. That was a gizmo the user 
substituted for the telephone transmitter 
(mouthpiece) by unscrewing the hand- 
set's transmitter and temporarily replac- 
ing it with the device, which consists of a 
small microphone surrounded by 12 
Touch-Tone "buttons." Unfortunately, if 
the phone's assembler gave the mouth- 
piece an extra twist when assembling it, 
nothing short of a special strap wrench 
would be able to get it loose. 

A much easier way to handle "port- 
able" signaling with Touch-Tones is 
Radio-Shack's Mini Tonedialer, which is 
certain to be the first of many similar 
gadgets. 

The device, shown in Fig, 1 , is a bat- 
tery-powered, shirtpocket-sized device 
with the standard Touch-Tone keypad 
arrangement on one side and a small 
speaker on the other. To transmit Touch- 
Tones, you simply place the side with the 
speaker against a telephone's transmitter 
(or a microphone), and press the key 
corresponding to the desired number (0- 
9) or symbol (* or #). The speaker repro- 
duces the corresponding tones for as long 
as the key is depressed. 

Unlike my old authentic telephone pad 



that had to be carried around in a briefcase 
or in a small camera bag, Radio Shack's 
unit actually fits in a shirt pocket because 
it measures only 2.4 x 4.4 x 0.7 inches. 
(You can even button the pocket of a 
Western-style shirt with it inside.) Its 
overall weight, including batteries, is 
about 1 .5 ounces — less than that of some 
pocket pens. 

What makes all that possible, of 
course, is the integrated circuit. The en- 
tire dialer consists of a single IC that 
generates the tones; a miniature crystal 
for the time-base reference; a transistor 
"output" stage that drives a 1.6- inch 
speaker; three resistors, and a capacitor. 
Except for the speaker, everything — 
including the batteries — is installed on a 
printed-circuit board whose foils also 
serve as the switch contacts. The low 
parts -count is the reason the whole thing 
costs only about $35. 

Setting FM levels 

Lately, it seems that there's a lot of 
commercial VHF and UHF FM gear 
floating around the surplus dealers and 
flea markets. The stuff is obviously good 
because I've worked on many that were 
converted to the amateur frequencies. 
Often, though, I've found that the hob- 
byists get lost in the modulator. 

Actually, frequency-modulation sys- 
tems are rather simple; A typical block 
diagram is shown in Fig, 2. The output 
from the microphone is usually fed to the 
preamplifier through an R-C network 
(R 1/C 1 ) that serves as a low-pass filter to 
keep RF that might be picked up by the 
microphone cable out of the preamplifier. 
To equalize the loud and soft voice levels, 
the preamp's output is clipped by diodc(s) 
Dl . The clipper simply sets a ceiling on 
continued on page HO 



78 



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CIRCLE 20 ON FREE INFORMATION CARD 



m 

H 
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79 



COMPUTER CORNER 



Electronic worksheets for your computer 

LES SPINDLE 4 



THE BUSINESS SOFTWARE F-IE-ILD IS A 

dynamic market nowadays. Competition 
and improved technology are combining 
to make each new product just a little 
more sophisticated than the one that pre- 
ceded it. Computer programs now serve 
not only as proofreaders and gramma- 
rians, but also as program writers, teach- 
ers of languages and operating systems, 
and sophisticated accountants. But no 
single software development has had the 
impact of VisiCorp's (formerly Personal 
Software) 1980 introduction of VisiCalc. 

Dozens of current software releases are 
fashioned after the simple, but revolu- 
tionary, concept that VisiCalc 
pioneered — the micro as an electronic 
worksheet for financial planning. 

The "Visiclones" (as they are some- 
times referred to) enable the user to for- 
mat a "worksheet" of figures on the 
screen, then modify those figures in any 
number of different ways and see the re- 
sults of the modifications. 

Mathematical relationships between 
any of the rows and/or columns can be 
defined. Suppose, for instance, that you 
want the bottom row to be the sum of all 
the rows above it. That can be accom- 
plished with one simple command. Other 
mathematical calculations — -log and trig 
functions, percentages, etc. — can easily 
be accomplished in the same manner. 

If one item on the worksheet is 
changed, every other item whose value 
depends on that item is automatically 
changed at the same time. It is possible to 
add new rows and columns or to change 
the order of existing ones. Meanwhile, 
the items whose values depend on the new 
setups are also automatically changed. 

The program is an ideal tool for pro- 
jecting budgets, planning expenditures, 
and charting various business strategies. 
Printouts of the various combinations can 
be made, for a step-by-step presentation 
of the pros and cons of each strategy. 
Presenting the various phases of an opera- 
tion to a board of directors' meeting, for 
instance, can be both efficient and im- 
pressive. But even more important than 
that is the time saved by the user as he 
works out his options in the planning 
process. 

For example, suppose a retail sales 
manager wants to make an intelligent 
guess as to sales trends over a yearly 

"Managing Editor, Interface Age magazine 




FIG. 1 



period. He devices a format consisting of 
several variables, such as interest rates, 
his best-selling products, his slow- 
moving merchandise, the number of 
salesmen in the field, and the previous 
year's sales. To further enhance the 
credibility of the outcome, he takes into 
account the fact that in his line, winter is 
the heaviest selling season. With his for- 
mat completed, he enters all the necessary 
data, then begins to examine the results. 
His analysis will take much less time 
than if he had sat down with adding ma- 
chine, scratchpad, and a big eraser. His 
report will project sales for each of the 
next 18 months. After consulting with his 
associates, he will likely have dozens of 
data changes to enter when he returns to 
re-work the projections. But, once the 
initial program has been set up, making 
those changes is simple. 

How they're used 

How does a user format the worksheet 
to fit his particular application? Most of 
the programs are well-documented with 
simple commands and self-prompting 
menus that lead him step-by-step through 



the formatting process. Using his com- 
puter's available internal memory , he for- 
mats a model consisting of the rows and 
columns that he will need. The size of the 
model is restricted only by the available 
memory. Filing and retrieving of data is 
done using disks, so that is usually not a 
factor in the size of the worksheet model , 
Once the model is visible on the CRT 
screen, the user can decide how to define 
each row and column on the "blank" 
worksheet. Each coordinate location is 
assigned either an alphanumeric com- 
ment, a label (such as a row description), 
or a constant or formula that relates the 
contents of several coordinates to each 
other. When that is done, the worksheet is 
ready for use. 

Choosing a program 

With the number of products on the 
market, it is sometimes difficult to decide 
on the best one for your particular 
application. You are restricted somewhat 
by your computer's operating system, 
memory capacity, and microprocessor. 
Some versions are configured for a par- 
ticular computer and its specific opcrat- 



80 



How to get an 8-channel 

e for $349.50 



sc< 



Add our Model 8001 8-channel 
multiplexer to your present oscillo- 
scope: It's the perfect way to view 
and compare signals occurring 
at different points in a circuit or 
system — in their real time and 
amplitude relationships. As well as 
one of the best bargains in test 
equipment today. 

Now you can have multi-channel 
capability wherever and whenever 
you need it. In the lab. On the pro- 
duction line. In quality control. And 
service — on the bench or in the 

(field. All for just $349.50*! 
Just connect its eight 1-megOhm 
inputs to your circuit via the front- 
panel BNC connectors. It's flat to 
12MHz ( - 3dB at 20MHz) and will 

» handle digital and analog signals up 
to - 5V (10V p-p) in any combina- 
tion. There's plenty of flexibility, too. 
Thanks to a variety of switch-select- 



able display/output combinations, 
multiplexer rates and operating 
modes that enable you to view each 
channel individually or all, simul- 
taneously — with pushbutton cal- 
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control that's continuously variable 
from 0-75mV/cm/channel. 

The trigger input, with switch- 
selectable polarity, is assigned to 




View up to eight digital and/or analog 
Signals (up to 10V p-p) on your present scope! 



channel one with continuously vari- 
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you can choose a switch-selectable 
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It's simple: When you consider 
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be glad to tell you when you dial the 
toll-free number below. 

cimci 

GLOBAL SPECIALTIES 

70 Fulton Terr.. New Haven. CT 06509 
(203) 624-3103, TWX 710-465-1227 

"Suggested U.S. resale. Prices, specifications 
subject to change without notice 







Call Toil-Free for Details 1-800-243-6077 

During Business Hours, 9AM to 5PM Eastern Time 



OTHER OFFICES: San Francisco (415) 648-0611, TWX 910-372-7992, 
Europe: Phone Saffron-Walden 0799-21682, TLX 817477, Canada: L'en Finkler Ltd., Downsview, Ontario. 

CIRCLE 11 ON FREE INFORMATION CARD 



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You'll learn all about computers: how 
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Registor L 5- Logic Analyzer, 6* Gate Arrays. 1. Non-Technicat 
Manuals on how to use analyzers, how to get into the guts of the 
computer, what makes it tick, how to service it. S. Sample 
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Conti nenta I IL S, A Credi L Card Buyers Ou tside Connecticut 

CALL TOLL FREE 800-243-7428 

To Order From Connecticut or For Technical Assistance* Etc. T 

Call (203) 354-9375 
NETRONICS R&D LTD.k^ 

333 Litchfield Road, New Milford, CT 06776 

Please send the items checked below 

n ELF 1 1 "Beginners" Kit SI39.M 

□ R.F Modulalor S S.95 

FIlis S3 .00 for postage, handling and insurance 
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Connecticut Residents add sales lax 

Total Enclosed S 

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Once you've found the products, you 
can examine the specific features offered 
by each program to determine which is 
best suited for your applications. Follow- 
ing are some of the features to keep in 
mind as you make your choice. Keep a 
checklist handy as you shop. 

First, determine the size of the matrix. 
Find out how many rows and columns are 
possible and analyze your needs to see 
whether their capacity is sufficient for 
your applications. Be aware that it is sel- 
dom possible to use all the rows and col- 
umns at the same time since both are 
affected by the total memory- capacity of 
the computer. 

Investigate the arithmetic precision of 
the program. There are limitations on the 
number of digits that certain programs 
can accommodate, and they may affect 
you if your calculations involve very 
large or very small numbers. 

See whether the program allows for a 
"comment column." That is a position, 
of varying length, that allows you to write 
some description of the row beside it. The 
feature can be useful for complex transac- 
tions that require more description. 

Does the program include graphics 
capabilities? Bar charts and the like are 
sometimes desirable, especially for meet- 
ings and formal presentations. 

Is split-screen capability available? 
Some of the more advanced programs 
allow it, and it can be a tremendous asset 
in comparing the results of related plans. 

Can the program interface with other 
programs? If data from word- processing, 
general ledger, payroll, or other pro- 
grams at work in your system can be used 
directly by your worksheet, or vice- 
versa, the door is opened for a wealth of 
time-saving features. Suppose you are 
producing a written sales-report and 
would like to integrate a worksheet as part 
of the presentation. Without word- 
processor-interfacing capabilities, you 
would have to re-enter the entire sheet in 
order to integrate it into the report. 

For clarity of reading, the ability to line 
up figures in a row correctly is crucial. 
For instance, if the decimal points in the 
numbers 596.83 and 9344.7 were not 
aligned vertically, it would be hard to 
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Does the program allow for partial 
printouts? Can you print one row or col- 
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Is it possible to jump to one point in the 
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continued on page 108 



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83 



STATE OF SOLID STATE 



DC voltage-controlled switches 

ROBERT F. SCOTT, SEMICONDUCTOR EDITOR 



THIS MONTH WELL TAKE A LOOK AT A 

DC -control led switch that can replace the 
usual rotary or pushbutton used to con- 
nect various signal sources to the input of 
an audio amplifier. In this case, the selec- 
tor switch feeds the input to the graphic 
equalizer circuit that wc discussed in the 
June 1982 issue. 

National Semiconductor has just an- 
nounced the LM1037 and LM103S DC 
Controlled Audio Switches. Both are de- 
signed to allow any one of four stereo- 
input sources to be connected to the 
stereo-output lines. Channels are selected 
by applying a DC voltage level to the 
channel-select control pins. Features of 
the LM 1037/38 switches are: 

Wide supply-voltage range (5 to 30 
volts) 

Click-free operation 

Low distortion, 0.04% typical 

High signal-to-noise ratio 

High audio-input impedance 

Low audio-output impedance 

Wide control -volt age range (2 to 50 
volts) 

High input-impedance on select pin 








TABLE 1 




Parameter 


Min 


Typ 


Max Units 


Conditions 


Supply voltage 


5 


12 


30 


volts 




Supply current 
(LM1037) 




7 




mA 


V supply — 1 ^ 


Supply current 

(LM1037) 




10 




mA 


'supply — ^Ll 


Supply current 










V supply — '^ 

V supply — JO 


(LM1038) 




14 




mA 


Supply current 
(LM1038) 




20 




mA 


Voltage gain 


-0.2 







dB 




Signal handling 






3.2 


volts,™ 


V supply — i£ 


Distortion (THD) 




0.04 


0,1 


percent 


1 V, ma input (it 1 kHz 


S/N Ratio (CCIR) 




-100 




dB 


TV,™ input 6i 1 kHz 


Crosstalk between 












stereo channels 


-80 


-100 




dB 


1V™ (a 1 kHz 


Crosstalk between 












connected and 












unconnected 












channels 


-80 


-100 




dB 


1V ms jg 1 kHz 


Relative output in 
muted state 


-80 


-90 




dB 


IV^,® 1 kHz 













FIG. 1 



The LM 1037 has four control or channel- 
seleet pins; one for each stereo-input 
source. If no channel is selected, the outputs 
are muted and clamped to the DC output 
level. 

The LM1038 is designed so that chan- 
nels can be selected by BCD input pulses. 
Two input pins feed clock-enabled latch- 
es so that the BCD pulses can be strobed 
from a bus. Or, the clock-input pin can be 
permanently enabled and the channels 
selected by DC voltage levels. A separate 
pin allows the output to be muted, via 
either a pulse or a DC level. 

To date, only preliminary specifica- 
tions (Table 1) on the LM 1037/38 have 
been released, so wc don't have complete 
details on the structure of the semicon- 
ductor device used as the switch ele- 
ments; but I'll bet that the switch is some 
form of FET. In similar analog switches 
from other manufacturers, JFET's, 
MOSFET's and CMOS (N-channel and 
P-channel FET's in parallel) have been 
used as gates or switches. Figure I -a is a 
functional diagram of a stereo-audio 
switch. When the control voltage is ap- 



plied, the switches close so that the input 
signals pass through to the output ter- 
minals. Figure 1 -b is the circuit of a basic 
analog switch using a JFET as the switch 
element. 

Figure 2 is the functional block dia- 
gram of the LM1037. The channel- 
selection details are outlined in Table 2 
(See page 86). 

Emitter and detector product guide 

The InfraredlPhotodetector Product 
Guide lists a line of GaAs IR emitting 
diodes and photodiodes, phototransis- 
tors, and photovoltaic cells. The IR emit- 
ters develop a wavelength of cither 820 or 
950 nM (nanometers) depending on the 
device. Detectors can be selected with 
maximum sensitivity specified at 
wavelengths ranging from 555 to 950 
nM. The guide includes dimensioned out- 
line drawings. — Litronix, 19000 
Homestead Road, Cupertino, CA 59014. 

Unique monolithic active filter 

National Semiconductor's MF10 is the 
first monolithic active filter that does not 



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TABLE 2 

Inputs switched to output pins 



Input channel 

Pin no. 

DC control 
conditions 
(pins) 

Output pin 



1 

3 
16 
18 



1A 

2 

VL 
VL 
VH 
VL 

10 



2A 

4 

VL 
VL 
VH 
VL 



1B 

6 

VL 
VL 
VL 
VH 

10 



2B 

8 

VL 
VL 
VL 

VH 



Output channel 



Low switching-level: VL < 0.8 volts 
High switching-level: VH > 2.0 volts 



1C 

11 

VH 
VL 
VL 
VL 

10 



2C 

13 

VH 
VL 
VL 
VL 



1D 

17 

VL 
VH 
VL 
VL 

10 



2D 

15 



12 



VL VL 

VH VL 

VL VL 

VL VL 



9& 10 

(MUTE) 




.^ SUPPLY 
T^ VOLTAGE 



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require external capacitors to operate, 
and is capable of performing a variety of 
functions. It is ideal for signal processing, 
telecommunications, modems, in- 
strumentation, and audio equipment. The 
center frequencies of all previously avail- 
able active fdters are adjusted with ex- 
ternal resistors and/or capacitors. The 
MF10 filter is unique in that the center 
frequencies of its various second-order 
functions are directly proportional to an 
external clock frequency and fixed at an 
accuracy of 0,6%, or directly pro- 
portional to both the clock frequency and 
external resistor ratios. Gain and selectiv- 
ity (Q) are adjusted using external resis- 
tors. 



The clock and three or four resistors are 
the only externa] components necessary 
to operate the MF10 so the device is less 
sensitive to external component var- 
iations. Frequency stability is directly de- 
pendent on the quality of the clock. A 
single clock can be used to drive an 
almost infinite number of MF10 filters. 

Unlike other available monolithic fil- 
ters which have been designed for a speci- 
fic function, the general -purpose MF10 
can perform a wide variety of functions 
including allpass, highpass, bandpass, 
and notch. Up to fourth-order functions, 
and any configurations such as Butter- 
worth, Bessel, Cauer, and Chebyshev 
continued on page 90 



86 



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STATE OF SOLID STATE 



continued from page 86 



CIRCLE 36 ON FREE INFORMATION CARD 



can be had by cascading the two second- 
order building blocks. The center fre- 
quency can be as high as 20 kHz with a Q 
of 500. Typically, the lowpass and band- 
pass outputs can sink 0.75 mA and source 
3 mA while the notch, allpass, and high- 
pass outputs sink 1. 5 mA and source 3 
mA. The devices come in 20-pin DIP 
packages and cost $3.50 in lots of 100. — 
National Semiconductor, 2900 Semi- 
conductor Drive, Santa Clara, CA 9505 1 . 

Optocouplers feature 
back-to-back LED's 

Motorola has introduced two new dual- 
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for AC input applications. The devices — 
the HIAAl and HIAA2 — consist of two 
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emitting diodes connected in inverse pa- 
rallel, and optically coupled to a single 
silicon phototransitor (detector) in the 
standard 6- pin DIP package . 

The Optocouplers can be used to detect 
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AC power and trigger a desired action . A 
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signal on telephone lines while providing 
isolation from the ring lines. The HIAA I 
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volts. The HIAAl has a current transfer 
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99. The HIAA2 has a 10% current trans- 
fer ratio and costs SI. 70 in lots of 1 to 
99. — Motorola Semiconductor Pro- 
ducts, P.O. Box 20912, Phoenix, AZ 
85036. 

Tunable low-pass 
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The MC 145414 dual-tunable low-pass 
filter from the Motorola MOS Integrated 
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growing family of CMOS switched- 
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The MCI 454 14 has a typical power 
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The device is offered in a 16-pin DIP 
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CIRCLE 34 ON FREE INFORMATION CARD 




CIRCLE 50 ON FREE INFORMATION CARD 



STEREO IMAGE EXPANDER 



continued from page 65 



stereo effect comes primarily from the 
studio's mixer-board. You can "A/B" 
the effect with the on/off switch. 

The majority of studio recordings are 
made from a mix of simultaneous "dry" 
sources and create an artificial image 
based on intensity differences between 
channels rather than on time and phase 
information. Even so, most of them will 
open up and sound more spacious — the 
speakers will become "transparent." 
Some recordings will do fascinating — 
and frequently spectacular — -things when 
turned loose by the expander. Try any of 
Pink Floyd's or Tomita's releases to real- 
ly put the expander through its paces. 

Background reading 

The first mention of loudspeaker 
crosscoupling and its effects appeared in a 
paper given by B.B. Bauer to the AES in 
1961 . A detailed exploration of the prob- 
lem, a solution and test results appear in 
an article entitled: 

"Head related two channel 
stereophony with loudspeaker 
reproduction" by P. Damaske, pp. 
1 1 09 to 1 1 1 5 of the Journal of the 
Acoustic Society of America, Vol. 
50. No. 4, Part 2, 1972 R-E 



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CIRCLE 27 ON FREE INFORMATION CARD 



SERVICE CLINIC 



Color-burst reference oscillators 

JACK DARR, SERVICE EDITOR 



A TV SET S COLOR-REFERENCE- 

oscillator signal, with a frequency of 3.58 
MHz (actually 3.579545 MHz), is a very 
important one. If it isn't present — with a 
few exceptions that will be noted soon- 
no color will be seen. Figure 1 shows how 
the video signal, with and without the 
reference signal, would appear on a 
scope. The frequency of the signal must 
be precise; if the oscillator shifts in fre- 
quency by as little as '/i-Hz, you will see a 
very obvious tint change. That means that 
the AFC must be very tight. 



The crystals used in the two circuits are 
not identical. They oscillate at the same 
frequency, of course; but apparently 
they're different cuts (one for use as an 
oscillator; the other for use as a filter) and 
neither one will work satisfactorily in the 
other circuit. (I determined that from ex- 
perience — and a whole afternoon of 
work!) 

The symptoms of oscillator failure are 
obvious. The black-and-white picture 
will be good, but there will be no color at 
all. If you run into that situation, the first 



vvyw 

WITH REFERENCE SIGNAL 



IP 



WITHOUT REFERENCE SIGNAL 



FIG. 1 



Two basic types of circuit are found in 
older sets, and are still in use in current 
ones. The older circuit is a crystal- 
controlled oscillator; the crystal de- 
termines the frequency, and an amplifier 
stage does the rest. The circuit can be 
made to free-wheel by killing the color 
sync. Its tuning can be set very near the 
precise point needed and when the sync is 
restored, it locks in and stays. Precise 
control is obtained by comparing the out- 
put of the oscillator with the color-burst 
signal, which is transmitted along with 
the rest of the TV signal . Many circuits of 
that type use an AFC circuit almost iden- 
tical to those used in horizontal -oscillator 
stages. 

The second type of circuit also uses a 
crystal, but not as the frequency- 
determining element in an oscillator cir- 
cuit. In fact, there is no true oscillator. 
The color-burst signal is fed to a pre- 
amplifier stage, and then through the 
crystal, which is actually used as a very - 
narrow-band filter. The signal from the 
crystal "filter" is fed to a very- high -gain 
amplifier stage (often mislabelled a 
"3.58-MHz oscillator"). It isn't an oscil- 
lator; what it does is amplify the burst 
signal, which makes it "ring" longer. In 
fact, there is still signal present when the 
next color-burst signal comes along, so 
it's clipped and becomes a standard RF- 
signal, which is fed to the demodulators. 
The frequency of those circuits isn't con- 
trol led . There 's no need to , because we 're 
using the color-burst frequency itself as 
the oscillator signal. 



and best test is to scope the output of the 
3.58-MHz circuit, looking for an RF sig- 
nal of the correct amplitude. Incidentally , 
you don't really need a wideband scope 
for that test. If there's a signal present you 
may see it as a blur, but the amplitude of 
the signal is the important thing; if the 
level is too low, the demodulators will not 
work properly. 

The first step is to check the active 
device (tube or transistor) by substitution. 
If that doesn't bring things back to nor- 
mal, check all the DC voltages around the 
stage to make sure that they're normal . As 
a last resort, try a new crystal, making 
sure you use the right type! If the crystal 
fails to work in the "oscillator" circuit, 
there'll be no feedback. In the filter cir- 
cuit, you'll seeRFon the input side of the 
crystal but nothing on the output side. In 
filter circuits, make sure that the color- 
burst signal is present, too. 

In some sets, (mainly the "oscillator" 
type) sometimes you can see an odd 
symptom. (I got a letter only this week 
that complained, "...I've lost the red. 
The screen is a bluish green but there's no 
color where it ought to be.") A color-bar 
signal shows no colors in the bars, but the 
white spaces between them will be a defi- 
nite bluish-green. That indicates that the 
oscillator is dead, but somehow there is 
enough of the color-burst signal getting 
through to the demodulators to make the 
screen glow bluish-green, which is the 
result of the phase of that signal. 

The problem isn't confined to older 
sets. In one solid-state set, a middle-aged 



Philco, the 3.58-MHz oscillator is a small 
1C op-amp. The original part has a history 
of failure at odd intervals. The best cure 
I've found is replacement with a different 
brand of IC — practically every one of the 
replacement-transistor/IC makers has a 
substitute for it. 

Loss of the oscillator signal kills the 
color. If, on the other hand, you lose the 
color sync, you get fairly bright color 
showing on the screen, but as "rain- 
bows" — narrow bands of red, green, and 
blue, slanted exactly like the bars you see 
when the horizontal oscillator's out of 
sync. The picture itself, though, will be 
steady. Start by checking for the color- 
burst signal; a dead burst-amplifier can be 
one cause of the problem. For a definite 
check, run a complete setup procedure on 
the oscillator. If the oscillator will make 
colors in the bars at the right places, but 
they float, the problem is narrowed down 
to the sync. In a few cases, the crystal can 
cause that. It'll be almost on frequency, 
but "right on the edge", and the sync 
won't lock. 

Another problem, found mainly in old- 
er sets, is good horizontal lock, but very 
poor color sync. Before running the setup 
on the oscillator, check the position of the 
horizontal-hold control. If the color sud- 
denly locks in when you move it toward 
the center of its range, you've solved the 
problem. 

The reason why the color sync is lost is 
that if the horizontal oscillator is almost to 
the fallout point, there will be a small 
phase-shift in the gating pulse. That's the 
pulse that " gates out" the color-burst sig- 
nal from the rest. If the pulse is off fre- 
quency, it gets there a little too late or too 
early and you lose the col or- burst signal, 
and thus the color sync. Always check the 
horizontal -hold control setting first; it 
may save you a lot of trouble! R-E 

SERVICE 
QUESTIONS 

SHORTED CRT 

There's a arcing In the neck of the pic- 
ture tube in this RCA CTC-58. My tube 
checker shows a heater-to-cathode short 
in the green gun (I have an Isolation trans- 
former for that kind of test). With the tube 
socket off, I can read 2SkVon the focus 



92 



pin of the tube. Please help!~D. W., Taos, 
NM 

There's a good chance that the CRT is 
bad. At times you'll find "particle 
shorts" between grids G3 and G4; G3 is 
the focus grid and G4 is connected di- 
rectly to the high- voltage supply. You 
□light try disconnecting the tube socket 
and HV lead, and discharging a medium- 
size capacitor (around 20-30 o.F) across 
the focus pin and ultor button (charge the 
capacitor from the B + supply). If there is 
a particle short there, that may blow it 
out. While the spacing between those two 
electrodes is very small, there shouldn't 
be any leakage at all there. Also check the 
focus circuit to see if any of its com- 
ponents have been damaged. 

RESISTOR BURNOUT 

In this Zenith 19HC50, resistor R221 
(1 Vrohms, Vk-watt) in the base return of 
the horizontal-output transistor, keeps 
burning up. I replace it, and It's out again 
in three or four weeks. Last time I used two 
3-ohm, >A-watt resistors In parallel to In- 
crease the current-handling capacity, but 
they burned up too. That resistor's very 
hard to get at; I'd sure like a permanent 
fix!— DM., Chicago, IL 

I know what you mean; it's always the 
hard-to-reach parts that have to be re- 
placed. Now — what makes a resistor 
bum up? Excess current! In your case, it 
can't be too much DC or the set wouldn't 
work at all . The only thing left is pulse- 
current, and there is a sizable pulse — 
about 1 5-volts peak-to-peak — across that 
resistor. 

There's also a 50-u.F electrolytic capa- 
citor across the resistor to bypass that 
pulse to ground. If it's open, the pulse 
could generate enough current to over- 
load the resistor. Replace the 50-u.F capa- 
citor, and stay with 1 -watt resistors to be 
safe. 

POOR FOCUS 

The focus is poor on this Zenith 
19EC45. 1 replaced the triplerand the HVis 
now OK, but the focus voltage Is only 500 
volts. When I disconnect the lead to the 
picture tube the voltage rises to 4.6 kV, but 
when I connect it again, the voltage drops 
back down. Could the focus electrode In 
the CRT be shorted?— A.G., Binghamp- 
ton, NY 

It's possible, but not likely. More prob- 
ably, there's leakage across the arc-gap in 
the CRT socket. Take it apart and check 
for carbon paths, etc. 

(Feedback: Bingo! A.G. says, "1 took 
the socket apart and found a burnt path 
from the focus pin to the CRT ground 
lead, which apparently was shorting the 
focus voltage to ground. Thanks.") 

ASSORTED HINTS 
Problem: Poor vertical size (two or 
three inches short of filling the screen) in 
a Toshiba TAC-9330 (Sams 1500-3). 



Solution: Check the two-ohm resistor 
from ground to IC302 (vertical osc/amp/ 
output)— the one I had read about five 
ohms. That isn't the only possible cause 
of the problem, but it's easy to overlook 
unless you're using a digital meter. 

Problem: Intermittent but repeated fail- 
ure of power-supply diodes in a Philco 
E-21. 

Solution: Try replacing the tripler, I did 
that and the set's worked well ever since. 
It must be that the tripler was in- 
termittent. 

Now for a request. I need a power 
transformer for a Lectrotech V-7 vector- 
scope. I wrote to the company, but got no 
reply; maybe you can help. 

Thanks to A.Y. of Lexington, NC for 
the hints. To answer your request, caii 
(800) 851-3584 and a nice fellow by the 
name of John Evans at Thdrdarson will 
try to help you out. I'm almost sure they 
have something that will do the job, since 
they have quite a few scope power- 
transformers in their catalog. 

HORIZONTAL HOLD PROBLEM 

I've got a Magna vox T936 with very poor 
horizontal hold. I'm not having any luck 
with it, and could sure use some advice.— 
CD., Hlghtstown, NJ 

Take out the AFC diode unit and check 
it for balance. Also, check all the resistors 
and capacitors around the AFC circuit. To 
make sure that the problem is in the AFC, 
ground the grid of the AFC tube and see if 
you can get a floating picture with one 
straight side. If you can, the oscillator is 
OK and the cause is due to the AFC sec- 
tion. 

(Feedback: "I tried the test and it work- 
ed — the AFC diode-unit wasn't ba- 
lanced. I also checked the resistors and 
found that a 68K unit that was supposed to 
drop the voltage to -I- 33- volts was open, 
even though it looked perfect. A new 
resistor and new diode unit fixed every- 
thing.") 

OPEN CAPACITOR 
BURNS RESISTOR 

I noticed a question here recently about 
an RCA CTC-3I that was burning up 
R163. You said it was the plate load for 
the horizontal oscillator, but I think it's an 
isolation resistor. It burns up because fil- 
ter capacitor C118B is open. Therefore 
the AC from the oscillator must go to 
ground through C119A, so it also goes 
through RI63 and bums it up. 

I've run into the problem in a number 
of 1967/1968 RCA chassis. 

Thanks toB.W., ofLoew's TV in Cen- 
tral City, NE for that information. 

SPECIAL RESISTOR 
This Portland RP-209HN had no sound 
or video, and only a faint raster. Those 
sets are made in Korea by the Tainan 
Corp. , and there is no Sam's Photofact for 
them as yet. However, I was able to get a 



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CIRCLE 33 ON FREE INFORMATION CARD 93 



New 
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CIRCLE 40 ON FREE INFORMATION CARD 



service manual from the U . S. office of the 
manufacturer; that address is Taihan 
{America) Corp., 8960 Lurline Ave., 
Chatsworth, CA 913 1 1 . Once that prob- 
lem was solved, however, I ran into a new 
one. Turns out that the cause of the prob- 
lem was R905, one of the critical 
"safety" parts. That being the case, I 
decided to order one from the company. 
That was until I found out that it could 
take up to six months to get one. Instead I 
used a 62-ohm Sylvania Flameproof re- 
sistor and it seems to work perfectly. By 
the way, there is a mistake on the parts list 
concerning that resistor — they list it as 
R05 instead of R905.— M.B. Danish, 
Aberdeen Proving Ground, MD 

VERTICAL PROBLEM 

/ had no vertical sweep on this RCA 
CTC-71. Tried changing C120, a 470-p.F 
capacitor. The raster came back and I 
thought that all was well. Not long after, 
however, the set came back with the same 
problem. I've been told that this capacitor 
has a high failure rate, but I'd like your 
opinion— R.C., Philadelphia, PA 

Considering that two of those failed in 
a short period of time, I'd try using a 
replacement with a higher working vol- 
tage. Many times if a part fails repeatedly 
it's due to the original rating being a bit 
too low. 

(Feedback: That was it — used a higher 
working voltage as you recommended 
and it appears to have solved the problem 
for good. Thanks!) 

FINDING INTERMITTENTS 
I've recently come across a new 
method for finding tntermittents. I've 
used it with good success and I'd like to 
share it with you. I use an electric engrav- 
ing-pencil — the type used for engraving 
names on personal belongings — as a 
"vibration tool . ' ' Just put a six-inch piece 
of rubber or plastic tubing on the end of it , 
set the pencil for its lowest speed, and 
hold it against the piece of equipment you 
are working on. That will dig out in- 
termittent solder joints, etc. quite quick- 
ly. In case you are worried that this 
method could damage your gear, NASA 
uses a ' 'shaker table" to test out its equip- 
ment and this tool is not nearly as 
rough. — R.E. Grist, Bayside, CA 

WEAK VERTICAL SYNC 

/ can stop the vertical roll on this RCA 
CTC-66 using the vertical-hold control, 
but the slightest disturbance causes the 
picture to begin rolling again—any 
Ideas?— S.C., Mentone, CA 

The symptoms you're describing indi- 
cate that the problem is weak vertical 
sync. Check the sync separator and all the 
DC voltages, etc. Sometimes that is 
caused also by leaky shunt capacitors in 
the vertical integrators. 

(Feedback: The sync separator, Q503, 
showed leakage. Replaced it with an 
RCA SK-3024 everything's fine.) R -E 



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The Memopak 's a 64K HAH pack which extends 

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and does noi inhibit the use of the printer or other 

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The unit is user transparent, and accepts such 

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With the Memopak extension theZXBI is 

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Call (7t6| B490735 to order. Have your VISA or 

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In Canada, call (41 61 787 144a. 
Mail orders send check or money order Sorry 
no CODs. Circle reader service card for 
Sinclair software catalogue 



CIRCLE 54 ON FREE INFORMATION CARD 




p Audio 
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CIRCLE 53 ON FREE INFORMATION CARD 



NEW PRODUCTS 



For more details use free 
information card inside back cover. 



CURVE TRACER, the model 501A. is de- 
signed to work in association with an oscillo- 
scope to display characteristic curves for a 
wide variety of discrete semiconductor de- 
vices. It displays the unique characteristic 




CIRCLE 151 ON FREE INFORMATION CARD 



curves for each type of semiconductor de- 
vice. By examining those curves, the user 
can determine all significant operating char- 
acteristics of the device under test. 

Test parameters measured include gain 
(beta), cutoff current, leakage current, output 
admittance, and breakdown voltage. The in- 
strument can be used to evaluate bipolar and 
FET transistors, diodes, SCR's, diacs, triacs, 
and other devices. 

The model 501 A is priced at $300.00 — 
B&K PRECISION, Dynascan Corporation, 
6460 West Cortland Avenue, Chicago, IL 
60635. 



SCANNER CONVERTER, the Scanverter 
C Wt> 7 , al lo ws com pi ete co ve rage of the 225 - 
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band when used with a standard aircraft- 
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space-shuttle radio links to Earth, military air- 
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rescue missions, FLEETSATCOM military 




CIRCLE 152 ON FREE INFORMATION CARD 

satellites, Federal government agencies' in- 
flight communications, and more. 

An exclusive development called 
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scanner capable of standard aircraft recep- 
continued on page J 00 



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CIRCLE 25 ON FREE INFORMATION CAHD 



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KTS HOME TRANNG 
DIGITAL SYSTEMS AND 
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YOU TO EXPLORE MICROCOMPUTERS, 
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Without question, microcomputers are the 
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NTS also offers courses in Auto Mechanics, 
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We 

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continued from page 95 



tion. No tuning or adjustments are necessary 
with the fully automatic converter. Reception 
for hundreds of miies is possible with the use 
of an outside antenna. 

A handy list of active nationwide UHF air- 
craft channels is included, and the unit comes 
complete with power cord, interconnect 
cable, and full instructions. 

The Scawerter CVR- 1 is priced at $99.95, 
plus $2.00 shipping. — Grove Enterprises, 
Inc., Brasstown, NC 28902. 

MINI CARD CAGE, model CCK19S, is a 
miniature card rack for STD bus microcompu- 
ter systems, it occupies only ,21 cubic feet, 




CIRCLE 153 ON FREE INFORMATION CARD 



yet holds up to 1 STO bus cards; it can easily 
be installed in desk-top consoles, video ter- 
minals, printers, controllers, or other equip- 
ment with limited space. 

The rack accepts either mother boards 
from Vector and other manufacturers, or card 
edge connectors with 28/56 .125-inch 
spaced contacts. It is form-compatible with all 
4.48-inch wide by 6.5-inch long STD 
microcomputer cards. It is shipped dis- 
assembled with ail hardware and can be 
assembled quickly. The captive screws in the 
cage T-struts permit easy locating of the 
mother board or discrete connectors. The 
model CCK19S is priced at $39.50— Vector 
Electronic Co., Inc., 12460 Gladstone Ave,, 
Sylmar, CA 91342. 

DMM, model 6502, features six versatile 
computing functions not available on similarly 
priced competitive instruments. A total of 14 
pushbuttons, combined with a self- prompting 
display, provides flexibility in the manipulat- 
ing and recording of data. Two storage regist- 
ers allow a display to be scaled by any slope 
and offset. A single null key stores a display 
as a "zero" value and automatically subtracts 
that value from all subsequent measure- 
ments. Two keys store any entered value as a 
reference, and display future measurements 
as a percent deviation from that value. High 
and low limits can also be stored, and a limit 
key then allows the display of values within 
those limits, or hi and lo annunciators if the 
measured value is outside of the limits. A 
start key initiates the continuous storage of 
maximum and minimum values. A min key 
similarly displays the minimum value. A reset 
key allows the instrument to return temporar- 




CIRCLE 154 ON FREG INFORMATION CARD 

ily to the DMM mode without losing any pro- 
grammed computation. 

A filter mode activates a binary weighted 
average of the last four measurement con- 
versions, assuring more accurate and stable 
readings in the presence of noise. To assure 
a rapid response to step changes, the filter 
function is automatically inhibited when suc- 
cessive conversions differ by more than 2% 
of full scale. All computing functions may be 
operated singly or chained, if desired, to per- 
form more multiple operations. 

The model 6502 is priced at $758.00.— 
Weston Instruments, 614 Frelinghuysen 
Avenue. Newark. NJ 07114. 

CIRCLE 00 ON FREE INFORMATION CARD 

ANTENNA TUNER, model PT-407, is a 
general-purpose tuner for 1.8-30 MHz to 
match antennas fed with coaxial or open-wire 
lines, single wire, or mobile antennas. The 
300- watt power rating makes it suitable for 
most amateur- radio setups. 

The model PT-407 has a large airwound 
coil, a large balun foropen-wire feed, and has 
ceramic insulation throughout. It is housed in 
an 8 x 4 x 7-inch aluminum cabinet with 



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THE 

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S70.00 



, Drop-resistant, hand-size V-O-M with high- 
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2 20,000 Ohms per volt DC ond 5,000 Ohms per 
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Rxl Ohms range- 
's Single range switch; direct reading AC Amp 
range to facilitate clamp-on AC Ammeter 
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Contact your local Triplett Distributor or Factory. 
Phone 419-358-5015, TWX 810-490-2400. 

Triplett performance . . . 
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1. AUDIBLE CONTINUITY TONE plus actual 
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3. BATTERY LIFE— 500 hour typical with 9V bat- 
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Contact your local Triplett Distributor or Factory. 
Phone 419-358-5015, TWX 810-490-2400. 

Triplett performance . . . 
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CIRCLE 46 ON FREE INFORMATION CARD 



CIRCLE 47 ON FREE INFORMATION CARD 



brushed-aluminum control panel and black- 
vfnyl cover. All controls are on the front panel; 
coaxial connectors are SO-230, and porce- 
lain feedthrough insulators are used for bal- 
anced line and single -wire inputs. 



P atom at Enginaafi 
Anlanna Timar 


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CIRCLE 155 ON FREE INFORMATION CARD 

The modal PT-407\s priced at $149.95,— 
Palomar Engineers, PO Box 455, 1924-F 
W. Mission Road, Escondido, CA 92025. 



MULTITESTER, model M110, has 21 
ranges, designed for servicing electronic 
equipment, gas appliances, heating, air- 
conditioning, and refrigeration equipment. 
The ranges are specifically chosen to place 
most measurements near mid-scale. For ex- 
ample: mid-scale on the low-ohm range, 5 
ohms, facilitates testing motor windings, re- 
lay, and contactor coils. 




CIRCLE 156 ON FREE INFORMATION CARD 

The model M1 10 features a fuse- protected 
ohm circuit, mirrored scale-diode-protected 
movements, and easy- to-read three-color- 
coded scale plate and front panel. Accuracy 
specifications for the model M11Q are: DC, 
±3% full-scale; resistance, ±3% of scale 
length; AC, ± 4% full-scale. Input impedance 
is 30,000 ohms-per-volt DC; 15,000 ohms- 
per-volt AC. 

The model M 110 is supplied with carrying 
case, test leads, batteries, and instructions, 
and is covered by a one-year warranty; the 
suggested retail price is $44.95. — Universal 
Enterprises, 14270 N.W. Science Park 
Drive, Suite 101, Portland, Oregon 97229. 



DIGITAL THERMOMETER, mode/ S7f, is an 
improved second-generation instrument that 
offers the versatility and performance of 



laboratory-bench thermometers. It is de- 
signed for situations in which temperature is a 
critical concern, particularly in electronics de- 
sign and manufacturing. The model 871's 
dual-channel capacity is practical and con- 
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outlet temperatures, do wet-bulb/dry-bulb 
measurements, and check other situations 
where temperature differential is important. 
The model 871 is supplied with a three- 
foot, beaded-junction sensor, so that (he user 
may begin taking measurements at once; it is 
the only thermometer sold with a sensor. A 
broad selection of optional probes is avail- 
able, and includes immersion, penetration, 
surface, air/gas, and hypodermic types to 
handle any application; custom and special- 
purpose probes may also be obtained. 




CIRCLE 157 ON FREE INFORMATION CARD 

The model 871 is priced at $225.00.— 
Keith ley Instruments, Inc., 28775 Aurora 
Road. Cleveland, OH 44139. R-E 



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101 



ANALOG DESIGN 



continued from page 62 



ve loped across R from that developed 
across R s . If it is desirable to make R s 
very large, ail you need do to compensate 
for the voltage, V RS , that is developed 
across it, is to either increase R G or reduce 
R x . The larger voltage now developed 
across Rq, subtracted from the increased 
voltage developed across R s due to its 
increased value, establishes a reasonable 
negative bias voltage. 

Before calculating the values of R x and 
R c , we should know what values of I D 
and R s are desireable. That can readily be 
done by averaging values that are found 
on the JFET's specification sheet. 

First determine the average pinch-off 
voltage, V P . It is midway between the 
maximum and minimum pinch-off 
voltages specified for the device. 

In a sim ilar f ashion, calculate the aver- 
age Idssi Ids Si the drain current when 
V GS = 0. 

Finally, choose a reasonable value for 
an a verage gate-to- source bias voltage, 



Yas 



It frequently is equal to about 0.4 x 



A!l those factors are then substituted 
into the following equation to determine 
the average quiescent drain current, I D : 



!n= lr 



/ IVasi \ 
\ IVpl / 



(17) 



Absolute values of V ns and V P are used 
so that polarities can be ignored. _ 

Now that we have determined I D , we 
can turn our attention to establishing a 
relationship between R s and V G , the 
voltage between the gate and ground. It 
is: 



IdRs 



(18) 



We obviously want to make R s as large 
as possible to improve stability, but there 
are some limitations. Voltages are de- 
veloped across R s and R tJ due to the pres- 
ence of I D . When 1 D is at its maximum. 




the sum of the voltages across R s and R n 
should be several volts less than V DD if 
the transistor is to operate in the pinch-off 
region. Hence (R s + R D )I D must be less 
than V DD . The value of R D is usually 
determined by other circuit requirements, 
so thai limits the value of R s . Once the 
maximum value for R s has been de- 
termined, the value of V G is found from: 






(19) 



But the values for R Ci and R x cannot be 
selected at random because of the pres- 
ence of the leakage current, I GSS . If AV GS 
is the allowable bias voltage variation in 
the design, AI D is the allowable drain 



InlmA) 



V GS <V0LTS> 



RG. 9— THESE CURVES are extremely useful when designing MOSFET bias circuits. The curves for 
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current variation, AI G ss ' s tnc amount the 
leakage gate current changes over the op- 
erating temperature range, and R s is the 
value of the source resistor, the parallel 
equivalent resistance, R P , of R G and R^ 
can be no larger than: 



Rp 






Al D R E 



AV<= 



Ale 



(20) 



Once you've calculated Rp, you can find 
R (; and R x from: 



Rg — 



R P Vn 



R P v 



(21) 



(22) 



Substituting that information into equa- 
tion 19, we can determine V G , 

Biasing MOSFET's 

MOSFET gates are insulated from their 
substrates and channels. Because of that, 
the leakage current is much lower than the 
loss of a JFET. Furthermore, this leakage 
current remains constant regardless of the 
MOSFET's temperature. 

Leakage current was a very important 
factor in bipolar device designs because it 
affected the output current. Collector cur- 
rent increased rapidly with leakage cur- 
rent and temperature causing the tem- 
perature and current to keep rising until 
the transistor, in many instances, de- 
stroyed itself. As for the MOSFET, that is 
not a problem because the output current 
here actually drops as the temperature of 
the transistor rises. 

As for bias voltage, no gate current 
other than leakage current flows regard- 
less of the gate's polarity with respect to 
the source. Despite that, n-channel 
enhancemenftdeplet ion-type MOSFET's 
are usually biased so that the gate is nega- 
tive with respect to the source. But they 
could, if desired, be biased so that the 
gate is positive with respect to the source. 
Enhancement-type devices, however, 
MUST be biased so that the gate is posi- 
tive with respect to the source. 

The circuits we used to bias the JFET, 
shown in Fig. 8, can also be used for 
biasing MOSFET's. There is one addi- 
tional consideration, however. Some 
MOSFET's have a lead from the sub- 
strate. If that should be the case connect 
that lead to the source of the transistor. 
Two curves, a plot of g m vs, I D and a 
plot of l vs. V GS , are useful when de- 
signing MOSFET bias circuits; a typical 
example of each of those is shown in Fig. 
9-a and Fig. 9-b, respectively. Be aware 
that those curves will, of course, vary 
greatly among different, types of 
MOSFET's; the curves for the specific 
device you are working with will be found 
on the device's specification sheet. 



For a specific V DS , calculating the val- 
ues for the circuit shown in Fig. 8-a is 
relatively easy if you follow these steps. 

1. Determine the g m required for the 
circuit being designed. 

2. Extend a line from that point on the 
vertical (g m ) axis of the plot of g m vs. t D 
found in the device's specification sheet 
to the curve itself. Drop a vertical line 
from the intersection point to the I u axis. 
Where that line crosses the I D axis is the 
desired value of I D . 

3. Following a procedure similar to 
the one in the last step, use the value of 1 D 
to find the desired value of V [iS from the 
plot of I D vs. V cs found in the device's 



specification sheet. Once that is done, the 
values of I D , V GS , and V DS are known. 

4. Calculate R s . For the circuit shown 
in Fig. 8-a, it is equal to V os /I D . 

5. As the voltage across R D must be 
equal to I D R D . V DD must be equal to I n R D 
+ V RS . 

The design procedure is somewhat 
more complex when working on the bias 
network for the circuit shown in Fig. 8-b, 
Here, the bias voltage is the sum of the 
voltage across R s , asjust determined, and 
the voltage across R G . If the voltage 
across R G is to be positive with respect to 
ground, the voltage across the resistor can 
continued on page HO 



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EQUIPMENT REPORTS 



continued from page 34 



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Enclosed in a matching 19- inch rack- 
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Both the input and output impedances 
of the DP4044 are 50 ohms. The DP4044 
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We measured the insertion loss of the 
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We found the DP4044 to be quite 
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It is housed in a lO'/i-inch wide X 
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very little insertion loss was noted. 

In the loudness position, the bass and 
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continued from page 70 



HfTEfltUTlOHAL CRYSTAL UFO. CO.. INC. 
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Normal tape movement, no audio 

A Sanyo M1000 cassette recorder ran 
nicely, but had no audio output. Rotating 
the volume control back and forth did not 
generate any sound from the speaker. A 
1-kHz signal was injected at the volume 
control, but there was still no sound. Even 
when the signal was injected at pin 9 of 
the audio -amplifier IC nothing happened. 
An electrolytic coupling-capacitor was 
soldered to pin 1 3 of the IC and connected 
to an external speaker, but there was still 
no output. 

Although the voltages at the IC were 
near normal, the IC was determined to be 
defective. Another LA4I00 power- IC 
was installed and that solved the no-sound 
problem. 

In summary, troubleshooting portable 
cassette-recorder/players is no different 
from working on other cassette players. 
You may find the components a little 
more compact and closer together but — 
then again — you may find fewer com- 
ponents to worry about. In fact, working 
with portable units can prove to be a 
pleasant diversion. R-E 



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COMPUTER CORNER 



continued from page 82 



suddenly switch to column A, row 3 if 
you need to access that information? 

Can data be stored separately from the 
model? For instance, do you have to ac- 
cess the model itself in order to check the 
contents of row 5 (say that's for August), 
or can you access a separate file that will 
indicate the August sales? 

Is there backup capability during the 
model-construction process? If a power 
failure or operator error occurs, will the 
entire model be lost , or is it backed up as it 
is created, so that only a small part of the 
work will have to be repeated? 

Several computational features can 
make significant differences in the 
flexibility of your system. Are boolean- 
algebra functions (and, or, nor, etc.) 
available for problems involving logic? 
Does the program allow for nct-present- 
value computations that are often neces- 
sary in financial projections? For 
engineering and statistical projects, are 
roots and exponential functions avail- 
able? Can the program compute per- 
centages of increase; for instance, can it 
be determined that column A (sales for 
summer months), was 45% down from 
column B (October-December sales)? 

All those features — and more — can be 
found among the various packages. You 
should investigate all the features offered 
by a package before committing yourself 
to it. 

Where do you begin your search? The 
tried-and-true VisiCalc (VisiCorp, 2895 
Zander Rd., San Jose, CA 95134) is a 
good place to start. Originally available 
just for the Apple 11, the program is now 
available for the Atari 800, the IBM Per- 
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If you are using CPIM, your choices 
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10028) (see Fig. 1), Microplan (Chang 
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ware, 3 Corporate Square, #700, Atlan- 
ta, GA 30329), SuperCalc (Sorcim, 405 
Aldo Ave,, Santa Clara, CA 95050), 
Multiplan (Microsoft, 10700 Northrup 
Way, Bellevue, WA 98004), and Calc- 
Star (MicroPro, 1299 4th St., San Rafael, 
CA 94901). 

Phase One Systems (7700 Edgewater 
Dr. , Oakland, CA 9462 1 ) produces Mas- 
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The business-software market has its 
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HEART RATE MONITOR 



continued from page 48 



you cannot divide by zero. When the 
Heart-a-Matic is first turned on, there is 
no guarantee as to what data will be 
present on the data bus. The 4508 that 
controls the bus at power- up will come up 
with data that seems to vary with the 
particular IC used. In a nutshell, there is 
no guarantee that there won't be all zeros 
on the data bus when the power is first 
supplied. The problem is resolved by 
IC22-e. It is configured as a haif- 
monostable that outputs a pulse about one 



and a quarter seconds long. The IC is 
connected, via diode D2, to the most- 
significant-bit on the data bus. 

When power is first turned on, the out- 
put pulse insures that there is some num- 
ber greater than zero on the bus. Without 
that half-monostable and the "Mickey 
Mouse Logic" (M 2 L) using D2. all zeros 
might appear and the Heart-a-Matic 
would try to divide by zero. If that hap- 
pened, the batteries would give out before 
the answer showed up in the display. 

The 1 2- volt power supply is made up of 

eight "AA" cells connected in series. Its 

output is fed to a standard 7805 regulator 

used in a slightly non-standard way. Be- 

continued on page 113 




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COMMUNICATIONS CORNER 



continued from page 78 



the volume level: The loud sounds are 
clipped, while the soft sounds are allowed 
to pass through unprocessed. 

Clipping the audio waveform causes 
distortion, and results in the generation of 
odd-order harmonics. For example, if the 
modulating signal is 1.5 kHz, clipping 
will produce substantial output at the third 
harmonic of 4.5 kHz and the fifth 
harmonic of 7.5 kHz, which are outside 
the upper narrow-band FM limit of 3 kHz. 
A low-pass filter consisting of R2/R3 and 
C2/C3/C4 strips out everything above 3 
kHz before the signal gets to the next 
modulation amplifier. 

The output from the amplifier is fed to a 
potentiometer, R4, which serves as a 
"deviation" (modulation level) adjust- 
ment, and then on to a varactor diode 
that's connected to the master oscillator, 
In that type of circuit it's necessary only 
to adjust the deviation control until the 
test equipment indicates the desired de- 
viation. 

Confusion sometimes sets in if a sepa- 
rate clipping adjustment is provided. 
Note that in the circuit shown, the clip- 
ping level in relation to the microphone 
signal is fixed; it's established by the pre- 
amplifier's gain and by diode DI. You 
will often find that there's a gain control 
for the preamp, or a level adjustment be- 
tween the preamp 's output and the clip- 
per; either way, you can set the degree of 
clipping for a specific level into the mic- 
rophone, or tailor the clipping level to the 
voice level of a specific user. Just remem- 
ber that the transmitter's deviation — the 
modulation of the RF signal — is set with a 
single control. R-E 



ANALOG DESIGN 



continued from page 103 



be found using equation 19. Com- 
plications arise if that voltage must be 
negative with respect to ground. Now the 
upper terminal of R x should no longer be 
connected to + V DD , but is instead con- 
nected to a negative supply. That supply 
is called — V GO - Equation 19 still ap- 
plies, except that — V GG is substituted for 
V DD . The values of R x , Rg> an d ^s are 
still found as outlined above for the JFET. 

Transistor applications 

From here on , we will concentrate on 
designing practical circuits that use bipo- 
lar and FET transistors. We will start with 
small signal audio applications and con- 
tinue our discussion detailing high fre- 
quency circuits, feedback, and so on. 
Regardless of what type of circuit you are 
designing, you will need to apply the 
material we've detailed over the past two 
months if you are to be successful. R-E 



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TRUCK TARPAULINS 



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FREQUENCY SYNTHESIZERS THEORY AND DESIGN (Second 
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boss. Designed for use 
16 and Loner® model 




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soldering instruments. 




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TL194 &emza£ 



gak ^^T » A com P lete soldering 

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For more information, see your local EDSYN Service 
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helpful checkup quiz, every few pages— answers to be found on the 
following page. And at the end of chapters, you will find representative 
questions listed under the five amateur-license grades. 
CIRCLE 112 ON FREE INFORMATION CARD 

PET BASIC: TRAINING YOUR PET COMPUTER, by Ramon 
Zamora, Robert Albrecht, and William Scarvie. Reston Publish- 
ing Company, Inc., Reston, VA 22090. 310 pp including appen- 
dices and Index; 5% x 6% inches; softcover; $12.95. 

Ifyouareanewcomertothe PET, you'll find that each ch apter i n th is 
book has been written for those learning to use the PET. There are 
many examples, do-it-yourself exercises, and fun-filled explorations. 
The text will encourage the user to experiment and try out the numer- 
ous features and capabilities of the PET; it even shows how to create 
graphical images on the PET screen without difficulty. 

For those who have been PET owners for some time, this book will 
prove to be a handy reference source, and a means of discovering 
new things that the PET can do. Each chapter includes a set of 
exercises for review that will help the owner to learn more, and 
develop greater skill in using that dynamic machine. 

CIRCLE 113 ON FREE INFORMATION CARD 

INTRODUCTION TO RADIO FREQUENCY DESIGN, by W.H. Hay- 
ward. Prentice-Hall, Inc., Englewood Cliffs, NJ 07632. 333 pp 
Including Index; 7 x 9Vs Inches; $27.95. 

This book is designed for three specific reader groups: the working 
engineer, scientist, technician, or manager; the student of engineering 
or computer science, and the electronics hobbyist, including the radio 
amateur. 

A central theme emphasized throughout the book is simplicity. More 
formal treatments of individual subjects are found in the references 
listed at the end of the individual chapters. Mathematics is used in the 
text as required to convey information to the reader. 

The individual chapters cover: low-frequency transistor models, 
filter basics, coupled resonator filters, transmission lines, two-port 
networks, practical amplifiers and mixers, oscillators and frequency 
synthesizers, and the receiver: an RF system. R-E 

CIRCLE 114 ON FREE INFORMATION CARD 




13 



IT TAKES THKK SKIN 

AND GUTSTO MAKE ATOUGH 

TOOLCASE. 

With rising production costs and smaller profit margins there 
must be a really strong commitment to excellence if superior tool 
cases are to continue being produced. 

Piatt is making this commitment. Their thick skinned tool cases 
are still made of the finest, high grade industrial materials. (Like 
durable ABS thermoplastic, for instance.) 

Their guts still feature the industries only one-piece molded 
pallet? There are no seams, stitches or rivets— the pockets can't 
tear loose. 

And Piatt has the only one year warranty on case and pallet. 

So, contact Piatt for complete information on their full line of 
tough, durable tool cases and your nearest distributor. 

•Pat. No. 3,880,285 



plCLtt 



Cases for business and industry. 
2301 S. Prairie Ave., Chicago, M. 60616 1312) 225-6670 



112 



CIRCLE 31 ON FREE INFORMATION CARD 



CIRCLE 41 ON FREE INFORMATION CARD 



HEART RATE MONITOR 



continued from page 109 



cause R27 is placed on the ground leg of 
the regulator, we are able to trick the 
device into putting out six voits instead of 
the standard five. That operating voltage 
was chosen for the Heart-a-Matic to pro- 
vide a compromise between battery life 
and reliable operation. The monitor 
draws an average of 60 milliamps during 
operation allowing long battery life. 

A low-battery warning is provided by 
R47, Q3, and SCR1. The voltage at the 
base of Q3 determines the voltage drop 



across R46. When it reaches a particular 
level, enough current will flow through 
the resistor to provide sufficient current to 
trigger SCR1. When the rectifier fires, 
the signal is routed to the decimal points 
of the display with the help of another bit 
of M 2 L logic, causing them to remain lit 
constantly. Diode Dl allows the beep 
generator to continue operating, and re- 
sistor R7 was chosen to make the decimal 
points light up much more brightly than 
they do during the heartbeat— so there 
will be no mistaking that the batteries are 
getting low and should be replaced. 

The trip point of SCR1 is set with R47 , 
a 500 kilohm multi-turn potentiometer. 



Once the decimal points light, the SCR's 
latching action will keep them lit. Note 
that if the Heart- A-Matic is rapidly turned 
on, off, and back on again, the low- 
battery warning will appear. That's be- 
cause C25 has not had time to discharge 
completely and the remaining charge 
fools the low-battery circuit into thinking 
that the batteries — not the capacitor — are 
not putting out enough voltage. A wait of 
about ten seconds is sufficient to prevent 
that from happening. 
Now that we know how the Heart-a- 
Matic works, the next step is to build one. 
We will show you just how that is done in 
the next part of this article. R-E 



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CIRCLE 42 ON FREE INFORMATION CARD 



MICROWAVE TV 
CONVERTERS 



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a 7 MICROWAVE PREAMP STAGES lor maximum g»m 

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CIRCLE 44 ON FREE INFORMATION CARD 



CIRCLE 45 ON FREE INFORMATION CARD 



113 



MARKET CENTER 



SATELLITE TELEVISION 

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Don't spend too much — call us! COMMUNI- 
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SATELLITE TV antenna, 1 ft. fiberglass, com- 
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also. TR1-STAR COMMUNICATIONS, Box 843, 
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SATELLITE television ... Howard/Coleman 
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SATELLITE Super-Mixer: DBM-4150A. Clean up 
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LAST CHANCE for FREE $200.00 value TVRO 
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SATELLITE equipment catalog. Over 25 of the best 
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g 

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Satellite — 

Computer — 
Test Equipment — 



DISCRETE 70 MHl PLt - FItrjIicM NEW video demodulator MM - 
out trie need for in id divider. [7D MHz I.F.f Gun in teed tracking 
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Kil (WI-OltHC) tl2*-35 

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TUNEABLE AUDIO DEMODULATOR - Tunes Irom Si to 8 2 HH; 
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Bare Board (MI1-020S) 11*55 

Too Boards IHSI'DZ IB) 35 95 

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carriers and neat what you've oven rnissins 

Bare Board I R8Z-010B1 S24 95 

Kit (Rtl-OIOKI ..mS5 

At T (111-0107) JW.35 

ID— OH IS ADAPTOR - Adapts mrmal-VOHor DVM to measure Iron, 
001 ohm to 5 ohms using single 9-voll bitter*. Super simple cali- 
brations. 

Ban Board (M2-100K) SH-95 

Kit (MMMKI H5-95 

A S T (MSMOOlt »9.S5 

MODEM — Bell 103 1300 bpsl compatible Answer /Originate modem 
No acoustic coupler required RS-232 serial I/O 

Bare Board ( Rt 1-1 008; '. II4.SS 

Kit(RSI-lMK) (69.95 

A 1 T(Btl 100T1 (99.95 

All prices Include comptele and contprabermve, drKurnenLation, 

pottage and handling C-D.D orders accepted. CjJI or write for 

cjtalog Dealer mqurrrts rrorflas. 



Digicom Engineering, Inc. 

P. 0. Box 1656. Kodiak. Alaska 396 15 
907-486- 5 1 1 8 907-486-62 1 5 

OPEN 10 AM TO 8 PM PST 

DESIGNS IN CONSUMER ELECTRONICS 

DC TO LIGHT 



ierenl sections. Free satellite aiming chart and 
microwave interference handbook (510.00 value) 
included. $9.95. IMS CO., P.O. Box 8369. Rose- 
ville, MN 55113 

MICROWAVE TV down converter, assembled 
and tested S44.95, ktt $29.95, power supply kit 
S29.95. Fully illustrated instruction manual in- 
cluded. Satisfaction guaranteed. Check, MO, 
COD. XANDI, Dept. 41 , Box 25647, Tempe. AZ 
85882 

DRAKE satellite receiver with modulator installed 
only $969.00. Satellite and microwave catalog 
S1.00. TEM MICROWAVE, 22518 97th Ave. No.. 
Corcoran, MN 55374 (612) 498-8014 



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FANTASTIC 80 KQ CHANNELS 



New antenna ccnstruclmn plans plus bifl 8x 1 1 
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Global TV Electnjniics PQ Bqx2t9-f Mailiaoa FL 32751 



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The most complete weekly listings. We cover more than 
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Satellite TV Week 

P.O. Box 308. Fo/tunji. QJIfomlii 55540 
Caj 1 1 ol 1 1 ree r ( 8 00 } 3 5 S . S>99 7 . Call [ornl* (707)725.1476 



BUSINESS OPPORTUNITIES 

LAWYER Business litigation, patents, appeals. 
JEHOME FIELD, B 292, Brooklyn 11230. Phone 
(212) 434-0781. Eves. 434-1825 

ASSEMBLE profitable devices at home. Ex- 
ceptional opportunities — without Investment, 
ENTERPRISES, 1133-R, Linwood Place, Utica, 
NY 13501 

ATARI repair business. Start your own. Send $5.00 
for more information to: IRATA REPAIRS, 2562 
East Glade, Mesa AZ, 85204 

USED TV's— tougher the economy— more the de- 
mand. Get started in this lucrative part or full time 
busi ness o u t of your own home . Completed etails on 
how to buy, sell, price service tips, much more. 
$5.00. USED TV r S, Dept. RE, Box 19754, In- 
dianapolis, IN 46219 

PROJECTION TV ... Make 5200.00 + per evening 
assembling projectors ... Easy ... Results equal to 
S2.500.00 projectors ... Your total cost less than 
$15.00. ... Plans, lens & dealer's information 
$14.00. ... Illustrated information free ... MACROM- 
QAX, Washington Crossing, PA 18977, Credit card 
orders 24 hours. (215) 736-2880 

MAJOR Northern California electronic replace- 
ment parts retailer. Solidly established, high profit, 
recession resistant business. $750,000,00 includes 
all assets, ten year lease, and flexible terms. GBS, 
Inc. agt. (916)381-8020 

MECHANICALLY inclined individuals desiring 
ownership of Small Electronics Manufacturing Busi- 
ness— without investment. Write: BUSINESSES, 
92-R, Brighton 1 1th, Brooklyn, NY 1 1235 



HIGHLY 
PROFITABLE 



ELECTRONIC 



ONE-MAN 
FACTORY 



Investment unnecessary, knowledge not re- 
quired, sales handled by professionals. Ideal 
home business Write today lor facts 1 

Postcard will do, Barta-RE-X, Box 248, 

Walnut Creek, CA 94597. 



MAKE money selling electronics. Wholesale dealer 
catalog $5.00 (redeemable). ETCO, Dept. 533, Box 
640, Champlain, NY 12919 

MAIL order — electronic components— well es- 
tablished high profit market. Start your own busi- 
ness. I have the expertise and working tools to send 
you on your way to an exciting future. For further 
details write to: STAN L., 45 E. 17th St., Suite 1 101 
NYC, NY 10003 



McKAY SETS THE STANDARD FOR 

COMPACT AM RECEIVING 
ANTENNAS 

DA100D OUTDOOR ANTENNA and 

OA9-DL4 LOOP ANTENNA 

For specs & details contact these dealers 

HARVEY RADIO* BARRY ELfcCTrfDNieS Nan ■■■■•. - ■ : •, 

HENRY RADIO L .", ArtQftlcs "A 

GILFEFL ASSOCIATES Pir* Ridge. NJ 

EDHOND SCIENTIFIC CO- 0, "inaicn NJ 

ELECTRONIC EQUIPMENT DANK Vttma. VA ID C Area] 

P.HOMAR Tim pi. FL 

FRANK L. BElER RADIO JNC. JnflersGfi LA 

THE BASE STATION Conctwd, CA 

J. MAR ELECTRONICS Toronlo, Canada 

INTERNATIONAL ftAOlO WORLD INC Vmcouvh. Canada 

800/854-7769 Local -714/621-6711 



except 

Calif-. All 1KB, Hi wad 



Telex' 910-581-4990 

G. E. McKAY & CO. 
111 S College Ave. 
PO Sox 5000 

Claremont, CA 91711 



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SAVE 90% 



YES! you can save up to ?0S on 
a computer for home or business 
S150.00 buys a 4 MHz Z80A with 

64-KB & a real Front Panel 
$200.00 for a 24x80 CRT and the 

list goes on-A/D, D/A, etc 
Send for FRSC SR0CHURC TODAY I 

Digatek Corporation, Suite 1 60 
2723 West Butler Drive 
Phoenix A2 85021 

ROLL-YOUR-OWN TECHNOLOGY AND 
SAVE A BUNDLE 



REVERBERATION 
FOR ORGANS 



Solid state with controls for rever- 
beration and room size. 
EVERY ORGAN SHOULD 

OWN ONE. Stm4 for frstlt/ir - 

DEVTRON IX ORGANS, INC. 

6101 WAREHOUSE WAY 

SACRAMENTO. CALIFORNIA 9SS26 Depl. B 



Get active public service frequencies foryour 
area covering police, fire, government, 
emergency, aircraft, amateur and more, Send 
$2.00 along with your name and address, in- 
cluding zip code, to Betty Bearcat, n'o Electra 
Company, P.O. Box 29243, Cumberland, IN 
46229. 



CIRCLE 100 ON FREE INFORMATION CARD 




SANYO 

STK-0050 
$g20 

(Minimum 10) 



The LARGEST selection 
Japanese semiconductors! 



STY 

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SANYO 

2SD612 

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Matching XFMR 

JB-300 

440 

48 



(100-up) 
(Minimum 10) 4ge (10 _gg) "^T (Minimum 10) (Minimum 10 

(The above special prices are effective until October 1, 1982) 




Popular Diode 
GH3F (for SONY) 

95* 




semiconductors 



Tr*n- 
ttaton 

2SA497 
A50* 

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1.60 
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WtMSOA 16.50 17 00 17 50 

MRF454 22 60 23 60 24 60 

HRF454A 23 90 2*60 25 80 

MRF455 17.60 16 60 1*60 

MHF455A 16.60 i9 60 20 80 

MRF644 29 90 29 60 30 80 

MRF64S 30.60 31.60 33.60 

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PLANS & KITS 



FREE catalog 99 cent kits. Buy 2 get 1 free. 
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PRINTED circuit boards from sketch of artwork. Kit 
projects. Free details. DANOCINTHS INC., Box 
261, West! and, Ml 48185 

CABLE TV converters and equipment. Plans and 
parts. Build or buy. For information send $2.00. C & 
D ELECTRONICS, PO Box 21 , Jenison, Ml 49428 

LIGHTING display sequencers and controllers. 
Send SASE for information on plans, parts and con- 
sulting services. DESIGN SPECIALTY, 15802 
Spingdale St. #80. Huntington Beach, CA 92649 

SAVE steps, money. Use your telephones as an 
intercom. Plans $5.00. dB Enterprises, Box 453 R, 
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SPIES like our antennas, so do H AMs and SWLs. 
SDRE, Box 242, Blacksburg, VA 24060 (703) S51- 
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System gainover 45 dB. $2.00 for information. MINI- 
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APPLE II compatible. Highly advanced MMS bur- 
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FREE 1982 catalog; components, kits, P.C. board 
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8T95 

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DM8131 

OS8S36 



1.65 

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RS 232 
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RS 232 



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Linear, TTL, 74's. 



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TERMS: For shipping include $2,00 for UPS 
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{ -., hii-MM ■ J Tix. California residents add 6% Sals? Tex. We 

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INTERNALLY 

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10/S9.90 




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For 6955 ACP 343.95 
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53 25 


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375 


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1.25 


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7.50 


22/44 S/T. KIM 


2.95 


43/86 5/T, MOT 


6.50 


60/1 00 SI 00 Connector W/W 


455 


5071 00 3-100 CoflnactOr S/T 


3.85 



Full ASCII 

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£0804 -1,75 

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201 &« 

29014 14H 

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S0O3P 140 

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611o/20ie*/95 
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2101 

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2147 *5 .99 

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6224 255 
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8255 4,50 
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8279 9.50 
8810 4.75 
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6952 525 
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8532 17.9S 

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2764 (8**8,75 
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H95S 2706 r*50nSl 55 75 

12.95 Z7O6(850nSr 625 

1702A 5.75 

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ft 13-Ofli WHvorn »so 

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'■■:.!.(! :i! 
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UC40MVKI J: 

LHH^VCfi U 

K1I2H FiiKtier) G*rt* jtf 5 

TB-HOM.jV. 1SV| Si 

alibis :-,■/ i:vi 1: 

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AV51 D1 5A/1 IB3 (545 (, 



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V 95 

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83 



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1.28 
1.63 



56 



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SUPER IC CLOS 



7&H05K 

78M0Q 

78M.H. 

LM108AH 

LM300H 

LM301CN 

LM304H 

LM305H 

IM30QH 

LM307CN 

LM306CN 

LM300K 

LM310CN 

LM311EVCN 

LM312H 

LM317T 

LM316CN 

LM319WH 

LM320K-XX' 

UA320T-XX* 

LM32GH-XX" 

LM323« 

LM324N 

LH337K 

LM338K 

LM33QN 

LM340K-XX' 

LM340T-XX- 

l.'- j .}^;>-:»;- 



LM348N 
LM350K 
LU3S3CM 

LM360N 
LM372N 
LM378N 
LM377N 

LMSaOCM/M 

LM38thl 

LM363T 

LM386N 

LM387hl 

LM390N 

NE531V/T 

NE55EV 

HE5S6N 

ME561T 

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MES66H/V 

h«567V/H 

ME592N 

LM702H 

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LM7lONLrH 

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LMT15N 

LMT23N/H 

LM733WH 

LM73SM 

LM743CISiVH 

LM741CN-14 

LM747N/H 

LM748W/H 

LM760CN 

LH1310N 

MC1330 

MC1350 

MC1358 



74SOOI 

74SQ2 

74S03 

74504 

74S05 

74S09 

74S00 

74S10 

74S11 

74ST5 

74520 

74S22 

74S30 

74532 

74538 l 

74S40 

74551 

74S64 

74SS5 

74S74 

74586 

74iS112 

T4SH3 

74S114 



55.35 

t.49 

1.40 

2.96 

.99 

.35 

1-06 

1 R9 

3.25 

.29 

,96 

1.49 

1.25 

175 
1.70 
1,49 
1.26 
1,36 
1.30 
1,26 
4.96 
.95 
5.95 
6.95 
95 
1.75 
1.25 
125 
1.95 
1.20 
5.60 
98 
1.4S 
1-95 
3,75 
2.75 
1-25 
179 
1.95 
1.25 
1,40 
1.95 
3.75 
.39 
56 
19 95 
125 
1.76 
1.50 
2.75 
199 
.20 
.75 



1.t5 
33 



,30 

3.95 
1.90 
1-05 
1.95 



LM1414N 

LM1458CN/N 

MC1488N 

MC143SM 

LM149W 

LM1&55W 

LM1620N 

LM1650K 

LMtSOON 

LM2111W 

LM2901N 

LM20T7N 

CA30I3T 

■CA301BT 

CA3021T 

CA3023T 

CA3035T 

CA3Q39T 

CA004CN 

LM3053N 

CA3069N 

CA3060N 

CA3062M 

LM3065N 

CA3O80T 

CA3061H 

CA3092K 

CA3083N 

CA3086W 

CA3O60M 

CA3095N 

CA3097N 

CA3130T 

CA3140T 

CA314CN 

CA3160T 

CA310ON 

CA34tON 

MC3423N 

MC3460N 

S03524N 

CA36O0N 

LM3900N 

LM3905N 

LA43909N 

LM3S14N 

LHS915N 

LM3918N 

RC4131N 

HC4136H 

RC4151N 

RC4194TK 

RC4195TK 

ULN2001 

ULN2O03 

SN754S0+, 

SM7645lh 

SN?5452N 

SN75453W 

SN7E454IN 

SN75401N 

SN75492N 

SN7549arM 

SN75404N 

TL4&4CN 

TL49SCP 



.99 
59 
59 
1.50 
55 
56 
310 
1.75 
,90 
2.50 
2.95 
2.19 
1.90 
349 
2.99 
275 
1-29 
1.29 
1.4S 
3-19 
3-19 
4.95 
149 
159 
1,69 
1.69 
1.55 
50 
2.99 
3.49 
1.90 
1.30 
1.19 
240 
1.19 
1.95 
.59 
1.49 
3.95 



t a 

&a 
r.-5 
9L9G 

a to 

£90 

1.10 
3 70 
■i H 
6.40 

: 25 

^.50 
SO 



,120 
i BE 



74S124 
74S133 
74S134 
74S135 
74S136 
745138 
745139 
74S140 
74S161 
745153 
74S1S7 
745166 
745160 
74S174 
746 175 
74S166 
745194 
74S195 
74610Q 
745240 
74S241 
74S242 
743243 



745244 S2.93' 

745251 1.35 

745253 1,35 

745257 1.29 

745258 1.29 
745260 .75 
74S280 2.79 
745287 299 
74S28B 2.55 
74S37S 3.10 
74S674 3.10 
745387 2.75 

745471 7,05 

745472 7.96 

745473 7.95 

745474 9.95 
745476 0,95 

745570 5.75 

745571 6-75 

745572 6,05 

745573 695 

745940 290 

745941 200 



DIP 
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2POBition $ .99 

4 Position 1,19 

5 Posilion 1 .29 

6 Pcrtition 1 35 




7PoH|pan Si 39 

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9 POsiliOn 1 .65 

lOPoailran 1.69 



MUFFIN® FAN 




The deponoTable, low 
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EOUT SPECIALS 



ULN200-3- 2/$ 1.09 

741S06S 

74LS377 

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2/1.99 

jyi.tw 

6.05 
11 Cf- 



2M8121 3/11,00 

SJ02652 356 

74S287 1 95 

2758 EPROM 2.S5 
74173^1 10 5/190 
ISO* CPU 4.95 

8522 8.9S 

6S02CPy 556 



SOOOACPU 

2102 RAM 

4060 FlAM 

8X300 CPU 

745367 

2708 EPROM 8/29.95 

74LS93 3/1.00 



255 
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1.49 
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1.96 



2114 



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|40B| 949-7919 







ujs 






7400* 


.ts 


747? ■ 


.38 


74161 i .66 


7401 


.22 


7476 


.34 


74182 


60 


7402 


.22 


7479 


4.60 


74163 


57 


7403 


.22 


7460 


,49 


74164 


87 


7404 


.22 


7432 


55 


74165 


87 


7406 


.23 


7483 


.55 


74166 


1.20 


7406 


^35 


7485 


65 


74167 


1.95 


7407 


.35 


7436 


46 


74170 


1.69 


7409 


20 


7465 


1.75 


74172 


475 


7408 


J3 


7490 


3d 


74173 


70 


7410 


22 


7491 


.57 


74174 


59 


7411 


SB 


7492 


,45 


74175 


.85 


7412 


-29 


7493 


.45 


74176 


75 


7413 


.39 


7494 


,69 


74177 


.75 


7414 


.59 


7495 


.65 


74179 


1.34 


7416 


J9 


7496 


.65 


74T80 


75 


7417 


.29 


7497 


2.90 


74T61 


175 


7420 


22 


74100 


290 


74162 


.75 


7421 


35 


74107 


42 


74184 


2.25 


7422 


.29 


74109 


47 


74155 


2.25 


7423 


.29 


74116 


1.95 


74166 


0,05 


7425 


.29 


74121 


.29 


74188 


3.90 


7426 


-29 


74122 


49 


74190 


1-15 


7427 


.25 


74123 


.59 


741 SI 


1-15 


7429 


.45 


74125 


.39 


74192 


85 


7430 


23 


74126 


.44 


74193 


55 


7432 


.29 


74129 


.59 


74194 


46 


7437 


.25 


74132 


.69 


74196 


68 


7438 


.29 


74136 


75 


74196 


85 


7439 


23 


74130 


06 


74197 


85 


7440 


.19 


74141 


.79 


741S6 


140 


7441 


.79 


74142 


2.95 


74190 


139 


7442 


SI 


74143 


2.06 


74221 


1.10 


7*43 


,95 


74144 


295 


74251 


06 


7444 


.95 


74145 


-82 


74273 


105 


7446 


.79 


74147 


i 05 


74276 


189 


7446 


.79 


74146 


1.20 


74279 


75 


7447 


05 


74150 


1.09 


74203 


1 40 


7448 


.79 


74151 


.67 


74254 


3 SO 


7450 


.19 


74152 


67 


742B5 


3.90 


7461 


.19 


74153 


.87 


74290 


'i 25 


7453 


.19 


74154 


1-19 


74296 


95 


7454 


.19 


74156 


,76 


74385 


.68 


7469 


2S 


74166 


76 


74386 


56 


7460 


23 


74157 


.89 


74487 


F38 


7470 


29 


74156 


1,66 


74368 


88 


7472 


23 


74150 


2-49 


74390 


1-46 


7473 


34 


74160 


.88 


74393 


150 


7474 


.34 
1 


rTTaf 


3 

G -43 


74490 


150 


T4LS00S .26 


74L5113 


7413245 52.20 


74LS01 




:•& 


74L5114 


-43 


74LS247 


1,10 


T4LS02 




a 


74LS122 


55 


74LS249 


1,10 


T4LS03 




2B 


74L5123 


1.19 


741,5249 


1,19 


74LS04 




35 


7415124 


146 


74L5251 


1.40 


741SOS, 




20 


74LS125 


50 


74LS253 


1.40 


7*Lsoe 




a 


74L5126 


.52 


74LS257 


.65 


74LS08 




SO 


74LS132 


.79 


741.5256 


98 


744.510 




28 


74LS136 


.49 


74L5259 


295 


74LS11 




35 


74LS136 


.85 


74LS200 


65 


71LS12 




33 


74L5139 


,85 


74LS261 


2 49 


74L513 




47 


74LS145 


125 


74L5206 


,59 


74L5U 




S5 


74LS146 


149 


74LS273 


175 


74LS15 




G 


74LS151 


.79 


74LS275 440 


74LS2Q 




26 


74L5153 


79 


74LS270 


?; 


74LS21 




so 


74LS164 


1,70 


74LS283 


.99 


7JiS22 




•a 


74LS155 


1.19 


74LS5S0 


.09 


74tS28 




33 


74LS158 


99 


741S293 


.99 


74LS27 




33 


74LS157 


,85 


74L5295 


1.10 


74LS3B 




IA 


74L5159 


.75 


74LS296 


1.10 


7«.S33 




10 


74L5160 


1.05 


74US324 


175 


74LS32 




33 


74LS161 


115 


74L5347 


1.95 


74LSS3 




OS 


74LS162 


1.05 


74LS34B 


1.65 


74LSJ7 




4fl 


74LS163 


106 


74LS352 


1.10 


74tS38 




33 


74LS164 


LIS 


74LS353 


1,19 


74LE40 




23 


74L516S 


59 


741.5363 


1.49 


7M£IZ 




79 


74LS166 


2,48 


74LS36S 


60 


741.SJ7 




79 


74LS168 


1.15 


74LS366 


40 


74LS48 




•3D 


74L51B9 


1 IS 


74L4367 


.99 


7*L5S1 




2S 


74LS170 


1,99 


74LS38S 


.89 


74LS64 




28 


74LS173 


.88 


74LS373 


150 


74L556 




25 


74L5174 


.88 


74LS374 


150 


74LS73 




46 


74LS175 


59 


74LS375 


.89 


744.S7* 




4? 


74LS16S 


2.20 


74LS377 


156 


741,575 




65 


74L5190 


1.15 


74LS3&5 


1-95 


74LS76 




45 


74LS191 


1,10 


74LS380 


86 


74LS78 




«J 


74LS102 


.98 


74LS.rC 


1.95. 


74LSS0A 


ra 


74L5193 


58 


74LS394 


1.96 


74L5ES 


1 


13 


74L5194 


MB 


74LS305 


1.70 


741.586 




46 


74LS195 


55 


74L5399 


235 


74LS90 




07 


74LS196 


,89 


74LS424 


2-95 


74LS92 




78 


74LS197 


M 


7+LS668 


1,75 


74L593 




75 


74LS221 


1.15 


rmsBra 


229 


■■1LSM 




BG 


74LS240 


1.69 


81LS95 


1.69 


74LS9B 




38 


74LS242 


1,69 


81LS96 


1-69 


741.5107 


45 


74LS243 


1.69 


81LS07 


165 


74L5109 


46 


74LS244 


1.40 


61LSS8 


189 


74LS1K 


43 




VOLUME PRICING 






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4000 S 


.35 


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4041 


.26 


4084 


2.95 


400G 1.0& 


4&42 


.95 


4008 


229 


4007 


.25 


4043 


56 


4009 


225 


4ooe 


.35 


4044 


56 


14408 


2:95 


4009 


.46 


4046 


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14409 1235 


4010 


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4047 


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14410 12-95 


4011 


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4048 


59 


14412 12 95 


4012 


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14410 


405 


4014 


.39 


4051 


.10 


4501 


39 


401S 


.15 


4062 


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4502 


1.65 


4016 


55 


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65 


4073 


35 


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4076 


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36 CHANNEL UP 

CONVERTER FOR TV 
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1-3 pieces 529. 95 e; 
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Model 6301 



Modal CTC5R 



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Model AB-370 Q0.9U e 

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a 

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Model AB-28 $2.95 e 

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6ft 



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matching unit Miniature Uotkt , m . 2 1> 1 . 1 U « 
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J! 7415283(1 U 

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SCR'S and TRIAC'S 



IC45 

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True 5 AMP 200V 
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jjG 5 AMP 500V 
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Tide 16 AMP 400V 
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39 
tt 
49 

1.29 

i.n 

2.14 
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.» 

1.55 
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1 95 

1 34 

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TRANSISTORS 

375 «» 40 VOLTS TO-92 CAM 
IKW27 41 2*6028 .30 



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TL061CP 

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TL074CN 

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IL497«CN 



,U3 



G3 
1 09 
3. 60 



SPECIAL!!! 

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n 

Posilivt Votiage Be^ofetors 
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P41 64-773 



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SUPPORT CENTER 

STATIC RAM'S 

i?Kx8j 200NS24PIN 



16K I.2SJ8) J00NL3J4WN 9.35 

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1K (256x4) 2S0NS 16 PIN 1.75 

JK (1Kx4) 2CCNS 18 PIN Low Powe' 3,45 

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BKIIKxB) 450NS 24 PIN 

1EK (2K X 8) 460NS 24 PIN 

Single 5 Voll Supply. Intel Pin Oul 

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Single 5V Supply. Intel Pin Out 

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32x8 

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256x4 

256x4 

512 X a 



1024 x 4 Tristate 
1024x8 Tnsisle 
2046 x 4 Tristate 



Open Collector 16 PIN 
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18 PIN 



2.45 
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2.45 
6.95 
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CHIP SETS 



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5.95 


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4.65 


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4.65 


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7.95 


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13.95 


6810 RAM 


2.65 


6821 PIA 


265 


6840 


7,95 


6845 


15.58 


6850 ACIA 


3.15 


6652 


4. as 


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10'. DISCOUNT on 


5100 00 or more order 


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ZILOQ 


780A-CPU(4 MHZ) 6.25 


28OA-PI0 


6.10 


780A-CTC 


6.10 


Z80A-OMA 


15.95 


Z80A-SI0/2 


17.25 


zao-sto/9 


9.95 



8080 
FAMILY 

5.45 
4.4S 

6.95 
34.95 . 



8035 5.45 8224 

808OA 4. 45 8226 
6085A 6.95 B228 
8086 34.95 8251 
8253 
8255 
8257 
8259A 

UART'S 

AY3-1015A/ S1602P 
AY5-1013A 



60C36 CPU (CM0S}1 1.25 
8155 9.00 

8212 2.25 



J. 9 5 
225 
4.65 
5.95 
B.50 
5.05 
8.05 
7.50 

3.95 
4.50 



ECL RAM 

10414DC / HM2510 5.95 

256 x 1 BIT FULLY DECODED 15NS 16 PIN 

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93L422PC 1 K (256 x 4) LOW Power 1 4. 95 
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93422DC IK (256x4) TTL RAM 14.95 

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Active's Super 
Low Price 

ACT NOW WHILE QUANTITIES LAST 



$49.95 



OPTOELECTRONICS 



LEO 309 
UD 211 
IEDZ1Z 
LEO 220 
LED 222 
LED 2Z4 



1 ijrmRsI 
i-i 3mm dstfl 
T-1 hmrMw 
T-l-a/4 5nm firt 
T-l-3/4 Smm Green 
T-1-7J/4 Sftxn VAT. 



OJ*pl*y* 

FND 357 

FNO 5007IPL 322 

FND 507/TIL 321* 

DL T07/HiW 71 

DL 1113 

14 thqii is S*or«nr AlrAi Mum i 

[It t-416 

[4 r>j.t. U S«g(nerir AWu Num.] 




..-:i4-3 mm .31 

110 74 2.10 4K2C .31 

ILCISt.tS 41133 .ft 
MCT2 .91 



^ 



Refer to our previous 

AUGUST ad lor other 

devices not listed here. 

Active is your one stop 

source lor the widest 

variety of electronic 

components. Contact us 

for devices not listed and 

for volume quotes. 

Unless superceded next 

month, the prices will 

remain valid tor 60 days. 



UNGAR-PRINCESS UNE FOR 
MICRO SOLDERING 



6976 
6990 
6931 
6910 
5915 
6903 
6950 
6951 
6952 
6953 



ION. 3 Win tan 
Srtlr Iran Hour 

(mill sponos r« naotr 

1M KM On* 
15W Kul Unit 
:■ ,yt HMM 
Pboch Mil, Copper 
Scrt«1rirtr Mb. CcppW 
SHdt Nib. CcppTf 
PrwismnNio.HilKl 



II. 25 ,.>.. 

3 1! 6961 

1.K 6S« 

1!.S4 6939 

use BS 

13.05 6944 

I. to 6945 

1.10 G946 

1.10 6947 

2.04 698! 
6933 



9C7VMI n.s. mted 

ScnMorher Nio Puieo 

SfareN.y PIMtd 
Desoxsor XI. 3 rips 
Ccsmtr np 60 Em 

DBCMer T 50 D>» 
DBXtoar Tn .375 OIA 
Dewier T» 180 014 
DeSokKr I.j, S(X1M 
rxul-iivLir* Extrvny 
T05 fjtrasw 



2.M 
I.M 
Z.04 
39 69 
E.OS 
3.03 

t.os 

6.0S 
4.40 
3.40 

5.00 



PLASTIC ENCLOSURES 

by PAC N TIC 





HEK1HT 


CM5-125H 


1.50 1 ' 


CM5.2tX)K 


Z.Z5" 


CM6-225K 


2.X" 


CMS-jOOK 


3.25" 



WIDTH 

5.08" 
5.0B" 

6.06" 
6.06" 



MF.PTH 

5.25" 
5.25" 
6.25" 
6 25" 



PfllCE 
• 90 

into 

1230 
13.00 



F 1 I 



IMMtl UK tlKk. Crtt. Tw (M Vm 



1 



1 



5% CARBON FILM RESISTORS 

Awiable stock on alt 5% ilandjrd vakxts txttwten 1 OHM 
and 9.1 MEG OHM. Moltioles ol ZOO pel. per value 

1/4 wm_ 



Below 1000 pieces 
1000 pieces and more 
V! W*TT. 



.05 u. 



1000 p 



1 1000 pieces 
ea end mere 

-tnn- 



.06 m. 
.04 u. 



Himl- 



D-SUBMIK.ATURE RS232 TYPE 
CONNECTORS AT MINIATURE PRK 



HO. OF COHTXCIS 
9 



49-1 109P 
49-1 I09S 
49-niSP 
43.I115S 
49-1125^ 
4S-1125S 

JS ■-.-!, 

49-11375 

3 - SOCKET. F-flllO 




SPEECH EVALUATION BOARD 

LIMITED QUANTITY 

PLUG IN YOUR OWN EPROM AND 
IT SAY* WHAT YOU WANT IT TO SAY 

SPSB1 001-01 $159.95 



— SWITCHES — 



■up 

SL3-220 

055-10 

MIK-101C 

K5FS1033 

35-375 

33-371 

35-377 

35-37S 

35-37! 



6 »MP lOM* Met), SPOT ON NOKE ON 
M.nalure SWe SwXcll, DTOT 
DIP Switch, 10 P 
M mature Fujli&L 

finktluni 7^l^":..j , i:.- srtai Moron l 
Rpin Shtrrtcfl 6 Pwiqn. Shwimg. 2 Pdes 
Rsury Switch. 12 Pshlan. Siwlrng. i Pat 
Retfey SMicJi 5 ftftjticn tan Shoring. 2 P(4n 
Rotary s*iKti 3 Rnimyi tan Shorling. 3 Ft4H 
notary Switch. 4 PmiEppi. Stoft.tg. 3 pc&h 
hcury Switcti, 3 Pcfldoi. SncVnng. 4 pato 



1.30 

49 

.33 

2 30 
2.33 

2 30 
2 30 
Ml 

230 



NOW YOU CAN CALL US TOLL FREE 800-343-0874 $$%?££$ 



FAST — EFFICIENT MAIL ORDER SERVICE 

U S Customers F> Bos 8000 Wo; I borough Mass Q15B1 

Mass Residents Call |617| 366-0500 
Outside U.S. 5651 Ferttor Si Hit' I Guobec. Canada H4P INI 

Tel No IS141 731-7441 . Wen No 05-823554 twx No 610-421-3251 

Alt prices shown are <« u S Ooliars 

Foreign customers remit payment on mt I hank matt or postal money ortttr in II S cunency 

Minimum mail older SID - AdO S3 00 10 cover posidijc & hanilmiq 

Visit our new outlet in Wcslborourjh Massachusetts 

Visa and Mailercaro jcteineo 



Write for your 

free copy of 

Acfive's 

comprehensive 

catalog today 




w 



m 

oo 

m 

33 

U7J 
CD 

to 
119 



CIRCLE 74 ON FREE INFORMATION CARD 





13C-VAC LJOKT SEQUENCER KIT 

Ul^iy*. atcl Thii TtluMt IC md SCR kit s*flu*ne« tDmlputi. 
Th« ba*fd hii 10 output cn**^ «*=h „^ M 

output ptd owi li^ii up to 150 WHltl 0^ (a ^PojKakJ 

120VAC Pimpa (yO" 1 " Ch*»J Mniweud 
T* It. FmufM v a ■ i iCHe *p*td r-d luicd 
input, Kil conM* nwih HI parti r PC 
board and imtriKSiam. Sir? o! baird. 
4" x 8 QpfriLti !iom 120 VAC. 
C4725 it 5 .95 

10 NOTE SOUND SYNTHESIZER KIT 

Verv unique simple musie ^ynthninr f ntur« 1 Q idjuiUH* "01W„ 
.viflahlt pcl£h r vtriibta ipwd r fitahifW LED and individual or flow- 
ing naui. Mik< "fobot" ijouwli, Sp*5* 
war computer *ff«ti. #tc On* ol tht 
ma$i unuouai kit*. Circuit foa&iptt 3 
IC's HtdJ I J inmrn*' ftnnori ComphU 
Wilh lit paftl. PC board and inslruzlififli. 
S» of Boatd: 2,fl" x 4**, OpanEH from 
OV blEttry hot i ncl-j.de d| W722 »1T JS 

I ELECTRONIC SLOT MACHINE KIT 
flmiirtit Ktiotn Hot muthin* futum wound rTfocb, digit*! ra*d 
outi and fl»ih;ng LED Hi; 3 drtfttim ivmixii 
"ton.* up" orm it a iji**,. Whtn ill 
EYmbOli ?ra \he uuru m i ptc.il win' 
nar natt loundi. Cl«ui. uhtf 7 lC"i and 
13 (rantitliora. Kit comas compleia mtn 
ill p*rr,j„ PC board and lnilruclioni,S««i 
of bowd: 1x6" x 7". Operant from 9V 
bagury hot indudtdi. C4723 t29.95 

{ELECTRON FC DIGITAL DICE KIT 

Fun *id mei ling— thi* kit rapiacn conwn cmcuL dica. Faaturn 
I bright |umbo LEDS and r 'ioll f ' lound Spotd of roll ■? fully •d|int- 
■bst and via nop indivickiUEy I Circuit f 
uiti A IC'i and 10 transiitom, KH tomm 
oomplct* H>ih alt pirE*. PC beard: and 
jnilructioni. Siia of bovd: 4" * 4 8" 
CfwriiciliomOVbaiiiry (not included h. 
C4724 *1S.« 




j™.: 








CIRCLE 101 ON FREE INFORMATION CARD 



Microwave TV antennas. Best in the West! Rod 
disc type. Complete with cable, accessories, war- 
ranty, 52 dB $125.00. Dealers wanted GALAXY 
ELECTRONICS, 6007 N, 61st Ave., Glendale, AZ 
85301 (602)247-1151 

STAGGERED resistor assortment ViW 6% com- 
mon values 40 each. Less common 10 each. 500 
total $10.00 CI ELECTRONICS, P.O. Box 3034, 
Camarillo, CA 93010 

MAGIC TV machine. Amateur microwave receiv- 
ers, 1 yr. warranty, S99.95. MICRO, Box 3123, 
Temple, AZ 85281. We repair most brands of 
amateur microwave receivers. 

MICROWAVE down converters. Also UHF sub- 
scription TV kits. Catalog 20C. TROJAN ENTER- 
PRISES, 2920 Shelby, Indianapolis, IN 46203 

SCANNER -monitor accessories— kits and factory 
assembled. Free catalog. CAPRI ELECTRONICS, 
Route 1R, Canon, GA 30520 

FREE speaker catalog! Woofers, mids, tweeters, 
hardware, crossovers, grille cloth, plans, kits, in- 
formation, much more. Discount prices. UNIVER- 
SAL SOUND, Dept. RE, 2253 Ringling Blvd., Sara- 
sota, FL 33577 (81 3} 953-5363 

POLICE/fire scanners, scanner crystals, antennas, 
radar detectors. HPR, Box 19224, Denver, CO 

3021 9 

TRS-80 mod 3 cassette programs 16K mail-list and 
inventory list. $14.00 each, $20.00 both. Write SUN 
MERCHANDISE COMPANY, Dept. RE-1, 1739 
Embassy Drive. Jacksonville, FL 32207 

CABLE TV Secrets — the outlaw publication the 
cab I e compan ie s tri ed to ban, HBO , Movie C rtanne I , 
Showtime, descramblers, converters, etc. Suppli- 
ers list included. Send $7.95 to CABLE FACTS, 
Box 711-R Pataskala, OH 43062 

LIQUIDATING $100,000 inventory: speaker 
comes, gaskets, voice coils, spiders; also finished 
speakers, 50% - 75% below cost. Free list: ISE, 355 
Cowan Terrace W, Brownsville, TX 78521 

ANYTHING electronic located fast. Reliable ser- 
vice, details $1.00 SASE. W.K.M, 212 N. Milton 
Ave.. Baltimore, MD 21224 



SUPER SALE 



EPRIM's 

1-7 B up 50 up 

2716 (5V, 450nS) S3, 95 $3.55 CALL 

2732 |5V, 450nS) 7.8S 6.95 CALL 

2532 |5V, 450nS) 11.20 9.25 CALL 

STATIC RAM 



7.50 7.20 CALL 
2.10 1.70 CALL 



7.90 7.49 CALL 



6116P-3 (150nS| 
2114L-2(200nS) 

DYNAMIC RAM 

4164(200nS| 

MISC 

CPU Z80A $5.29 ea. 

CDP-1854ACE (LJART] $4.80 ea. 

16K RAM Expansion Kit 
for TRS-80 Mod 111 $12.95/8 

■jfc SUNTROMCS CO.. inc. 



12621 CRENSHAW BOULEVARD 
HAWTHORNE, CALIFORNIA 90250 



r.mi-:F HOURS '■ i 



IN CALIFOBKIA 



OUTSIDE CALIFORNIA TOLL FREE 



(213) 844-1149 1-B00-42PS77S 

Am Ordur: itO, 9IW- %%. Atcapt VISA. Maat.re.rd. Ch»ek or M.o. 



LATEST in video accessories!! Free shipping in 
U.S.A. Catalog $1.00. ELECTRONICS ET- 
CETERA, P.O. Box 826-L. Solvang, CA 93463 




MINI FM MIC 

Compact size, only 2"xl'W. Tfan&mil 
to FM fidici 0&-1GS MHj. ExMJJhona; 
audia qualily Traosmiis \\mto nigral up ' 
to &00 ft Compile KM loot, casa, bolterY 
a rflalnjclram OnryS13 95 A«S6ffibJed 
SIS 95 AGd S1 55 S4H pa Send 20c 
stamp lor b'ochure. 

S.E. Corp.. Boa 5I32-RE 
Vdlba Linda. CA. 92686 



COMPUTERS 

ATARI' 800™ 
COMPUTER SYSTEM 

aoOw I6K '3SOOO 
SODw'tEK >S99O0 

*800Compot» w/4BK 

**gS *825.oo 



ATARI PERIPHERALS: 



Plinth "885-- S60PO 

Dilk Df."810- «6» 
RKljri-«10- az«"> 

***"- | p" >iese 

J&yltekiP»l 

38k RAM- lTfise 

Bak Crl- 49"> 



Aalrvwdl ^ 
Wtssta Conv^ 32 50 
SucBikCut 
Aaa«m Edit- 4aWO 

Em Raktvs- 45f» 

Bavhotbatl- MP° 
Ch»s-32PO 



Pac-Man^*36.95 



{Diskette Storage BOX 

♦ HARD PLASTIC* 



5V 4i , 



J* 



2.95ea. 



i-* *4.75ea. * 



Bare Bones APPLE II 

W/O,, -48KRAM 

Keyboard 



Pwr. Supply 



$ 450. 



Microswitch: Power Supply ^ APPIE 
Keyboard : 5 amp.; Reference Man I. 
^79.95 : *124.O0 ; *18.O0 



* SPECIALS 

3inchMini FAN — ~'8.S5 
2111—^ 'j*5 
81 55— ~tl1.50 
EH2501 —•-**. 55 
AY5 1013A-*'295 

8202— — *29.95 

6522 — »- *5.2S 

2716lt5VI — t- U.50 
2732—^ *9.95 
B25S — *5.95 

b7«b e — *3L00 
MCEaoo — *7.75 
Hcsso: - '1495 

MC4850 J4.50 
MCB821 — *4.95 

8Pds. DIP 
SWITCH 

*1.35ei. 

( 1982' 
IC MASTER 

2\tals. 

$ S*95 



CONCORD 



1971 SO STATE COLLEGE 
AMAHEIM CALIF 92806 

(7141937-0637 »#, 

' MJ too & 

■lOMIMMUtD L«S[l'«OB(> 

'S S *iffi 'jjciSilfflb FREIGHT 



MONITORS 
ZENITH *ZVM-121 

12in. 15MHz./ GREEN Ptios. 

*1 13.00 
J.c's^kG-12'" 

12in. 19MHI. /GREEN Phos. 
Non- Glare Screen $1^jcn 

BMC^BM^i^A 

12in 15MHz /GREEN Phos. 

*95.00 
AMDEk^CM-B" "(COLOR' i j 

13in, /COLOR 11 

*375.00 



COMPONENTS 



\Diskette SALE!! 

'Wabash* 

5W 8*ich 
SS/SD* 22.00*25.00 

SS/DD 27.40 3040 

DS/SD o 34.90 

OS/OD3240 37.40 



REAL-TIME CLOCK 
CALENDAR (MSM 5832) 

Dfwalm Mono M*t«l Oat* CMOS J C 



Tnn«. Month. Data 

'emDrrtfvMd 


•torn. 1 


"H-l Dal* But 
-■Hi- JUdr*w 


*7.45 


' lr.lt r &ign»l 


XTAL 


■ 32 rtfiKlM itfll Conlrol S 235 


*BK PdW ii:p 




"Low taww Dmi.piiKrfi 



1 



If 

7412 

Mil 

74. 4 
7416 

m 



i I 



1 



m 
§1 

74 US 

§1 

Si 

7*tS6 



pthAHlC MH, 



in* 

Mp611G 200hi 



fc!l5 

3'1*!( 



NO P.O. BOX 

SHIPMENTS 



•139 

tibi 

HtClJSQ 

Kl]H 

■ICIXM 

i U3K 

LWJH 

luifti 

LUH1 

LM13IO 



fcfe-a-"* 



74 5C0 
M302 
N«l 

NWI 

745-5 
MSla 
J»5JJ 

hur 
hsii 

T*5*5 
J4SM 



T4S1H 
MSllQ 
MS 159 
HS1H 
Milt!. 
MS-91 
MSUJ 
MIMA 
MSJ40 
MSM' 
M1471 
F*H7? 



tPROMl 

il-DJ 129 a- 3 sh>«. 

jroc 7 99 9i | 3 95* 

?r-*ijvi 5« f4 SOu 

rM53M6 »fti flUii 

?7&l:,Yl 1490 9J9 39*. 

TUSJU? <i SO '>■>& 254 



mi 



cnjK 



f*D 



9 0O 

;«OJ\ PhO 9 00 
tut •« 

9501A '7 00 

MC99CQ 7 75 



CIRCLE 81 ON FREE INFORMATION CARD 



ramsaij the first name in Counters ! 



9 DIGITS 600 MHz $129f IRED 




SPECIFICATIONS 



PRICES 

tT.W»irrd.l. >w< 






The CT-90 is the most versatile, feature pecked counter Available for less 
than 5 3 GO .00! Advanced design features include; three selectable gate times, 
nine digits, gate indicator and a unique display hold function which holds the 
displayed count after the input signal ii removed Also, a lOmHi TCXO time 
base is used which enables easy xero beat calibration checks against WWV. 
Optionally, an internal ni cad battery pack, e sternal time base input and Micro- 
power high stability crystal oven time ba« art available. The CT-90, 
performance you can count cm! 



Range: 
Sensitivity: 

Resolution: 



Display: 
Time base 

Power 



20 Hi to 600 MH- 

Less than 10 MV to 150 MHz 

Less than 50 MV to 500 MHz 

OJ Hi (10 MHz range) 

1.0 Hi (60 MHi range) 

10,0 Hx(600 MHz r»nge) 

9 digits 0.4" LED 

Standard- 10.000 mHz, J.G ppm2<M0 D C. 

Optional Micro-power oveivO.l ppm 20-40" C 

8-15 VAC® 250 ma 




7 DIGITS 525 MHz $99f IRED 

The CT-70 breaks the price barrier on lab quality frequency counters. 
De I u xe features such *s three frequency ranges - each with pre- am p I i ii c at i o n, 
dual selectable gate times, and gate activity indication make measurements a 
snap. The wide frequency range enables you to accurately measure signals 
from audio thru UHF with 1 ,0 ppm accuracy - that's .000l%1 The CT-70 is 
the answer to all your measurement needs, in the field, lab or ham shack. 



SPRCIF1CAT10N& 


Range 


20 Hz to 525 MHz 


Sensitivity: 


Lets than SO MV to ISO MHz 




Leas than 150 MV to 500 MHz 


Resolution: 


I.0Hl(3 MHz range) 




10.0 Hz (50 MHz range] 




100.0 Hz (500 MHz range) 


Display: 


7 digjnO.4" LED 


Time base 


1.0 ppm TCXO 2CM0*C 


Power 


12 VAC® 250 ma 



PRICES 

CT-70 wired. I year warranty 

CT-70 Kit, 90 day parti w«. 

ranty 

AC-1 AC adapter 

BP-I Nicad pact + AC 

adapter/charger 



J99.95 

84.95 
3.95 

12.95 




7 DIGITS 500 MHz $79^ 

WIRED 



PRICE& 




MINI- 100 wired. 1 year 




warranty 


S79J5 


AC-Z Ac adapter for MINI- 




100 


3.95 


BP-Z Nicad pack and AC 




adapter/ charger 


12.95 



Here's a handy, general purpose counter thai provides most counter 
functions at an unbelievable price. The MINI- 100 doesn't have the full 
frequency range or input Impedance qualities found in higher price units, but 
for basic RF signal measurements, it can't be beat! Accurate measurements 
can be made from 1 MHi ell the way up to 5 00 MHz with excellent sensitivity 
throughout the range, and the two gate times Id you select the resolution 
desired Add the nicad pack option and the MINI- 1 00 makes an Ideal addition 
to your tool box for "in- the- field'* frequency checks and repairs. 



SPECIFICATIONS 



Range: 
Sensitivity: 

Resolution: 

Display: 
Time hue: 
Powert 



1 MHno 500MHi 
Less than 25 MV 
100 Hz (stow gate) 
1.0 KHz (fast gate) 
7 digits, 0-4" LED 
2.0 ppm 20-40" C 
5 VDC 8 200 ma 



8 DIGITS 600 MHz $159^ TRFn 

WIRED 



Range: 
Sensitivity: 




SPECIFICATIONS: 




Resolution: 



20 Hz to 600 MHz The CT-5 is a versatile lab bench counter that will measure up to 600 MHz 
Las than 25 mv to 150 MHi with S digit precision. And one of its best features is the Receive Frequency 

LOHtfrM MhT ***\ MHl Adtptcri which tums lhe CT " 50 *"* " di * il * , reRdoutfor **? receiver The 

.!.„ /(C/y, mh ra 1 adapter is easily programmed for any receiver and a simple connection to the 

8 difltts0 4" LED receiver's VFO is alt that is required for use. Adding the receiver adapter in no 

2.0 ppm2G-40*C wa ' t ' limits the operation of the CT-50. the adapter can be conveniently 

110 VAC or 12 VDC switched on or off The CT-50. a counter that can work double- duly" 



PBJCE& 




CT-50 wired, 1 year warranty 


1159.95 


CT-50 Kit, 90 day parts 




warranty 


1 19.95 


RA-1 K receiver adapter kit 


14.95 


RA-l wined and pre-program- 




med ( send copy of receiver 




schematic) 


29.95 



DIGITAL MULTIMETER $99 ^ IRED 




PRICES: 




DMTOOwtnd, 1 ytaiwanamy 


S99.95 


DM-700 Kit, 90 day parti 




warranty 


79.95 


AC-1, AC adaptor 


3.95 


BP-3, Nicad pack +AC 




adapter/ charger 


19.95 


MP-1. Probe til 


2.95 



The DM-700 offers professional quality performance ai a hobby tit price. 
Feature* include; 26 different range* and 5 functions, all arranged in a 
convenient, taiy TO use format. Measurements are ditptiyed on a large VA 
digit, '.■•■$ inch LED readout with automatic decimal placement, automatic 
polarity , overrarige ind icacion and overload protection up to L 250 volts on all 
ranges, making it virtually goof-proof* The DM-700 looks great, a handsome, 
jet block, rugged ABS case with convenient retractable tiEt bail makes It an 
ideal addition to inv shop. 



SPECIFICATIONS: 

DC/ AC volts: 100 uV to 1 KV S 5 ranges 

DCVAC 

0.1 uA to 2.0 Amps, 5 ranges 

0-1 ohms to 20 Megohms, 6 ranges 



current 

Resistance 

Input 

impedance: 

Accuracy: 

Power 



10 Megohms, DC/ AC volts 
0.1% basic DC vails 
4'C cells 



AUDIO SCALER 



For high resolution audio measurements, multiplies 
UP in frequency. 

• Great for PL tones 

• Multiplies by 10 or 100 
i 0.01 Hi re solution; 

$29.95 Kit $39.95 Wired 



ACCESSORIES 

Telescopic whip antenna- BNC plug . . . ♦ , S 7.95 

High impedance probe, light loading . . , 1 5.95 

Low pass probe, for audio measurements . . . . . 1 5,95 

Direct probe, general purpose usage .....♦.,.,. 1 2.95 

Till bail forCTTQ, 90, MlNMOO ,.,, 3-95 

Color burst calibration unit, calibrates counter 

against color TV signal T . . < . 14.95 



COUNTER PREAMP 

For measuring extremely weak signals from 10 to 1,000 
MHi. Small siie, powered by plug Transformer-included, 

• Flat 25 db gain 

• BNC Connectors 

• Great for sniffing RF with pick-up loop 
$34,95 Kit S44.93 Wired 



i-i iiyii, .1 : nil ihv. i i :. 

2575 BAIRD RD. • PENFIELD, NY 14526 



PHONLORDKRS 
CALL 7](i-5X6-3950 



i#!und Add 5- fni ^h.pp.ng 
oljitl Uv»-t*«i,ti'jij>l COD odd 
10 add II iO Nr.rtid*ft>v add 7 lax 



co 
m 

3 

m 
S 

CD 



CD 
CD 

ro 



CIRCLE 72 ON FREE INFORMATION CARD 



121 



CUSTOM electronic manufacturing, prototype, 
short production run, DAUS ELECTRONICS, P.O. 
BOX 831 , Angier, NC 27501 

RECORDS— tapes! Discounts to 73%; all labels; no 
purchase obligations; newsletter: discount dividend 
certificates: 100% guarantees. Free details. DIS- 
COUNT MUSIC CLUB, 650 Main Street, PO Box 
2000, Dept. 3-0762, New Rochelle, NY 1 0801 

DESCRAMBLERS gated pulse sinewave, 
transmitters, sniffers, bugfoiler, lineals, 
scramblers, schematics, boards, kits. Catalog 
S2.00. MSM ELECTRONICS, Box 252, Crom- 
pound, NY 10517 

SUPER-buy: microwave receiving systems, con- 
verters, satellite TVRO. Large selection of best 
quality products. Lowest prices anywhere. Free in- 
formation. Catalog $3.00. Satisfaction guaranteed. 
TOE, Box 343, Dept. R, Brooklyn, NY 1 1 £30 

USA subscription — TV stations (MDS) brochure. 
Latest and most complete information: exact tower 
locations, programming, equipment, ownership and 
more. Send $1 0,00 to TCE, Box 343, Dept. R, 
Brooklyn. NY 11230 

TEKTRONIX and HP 30 MHZ used oscilloscope 
$200.00. (714) 985-99S7, 

POWER-AMP sub-assemblies, 100 watts rms. 
.05% distortion, completely assembled and tested. 
quantity pricing available, free b rochu re . CLA XTO N 
AUDIO, 3174 Periwinkle. Memphis, TN 38127 



WANTED 

Ideas, inventions, new products wanted for presen- 
tation to industry. Call free 1-800-528-6050. Arizona 
1-800-352-0458. X831. 



UHF CONVERTERS 

DELUXE sine wave UHF converter. Sound out of 
TV like normal with only antenna connection to TV 
or VCR. Kits $175.00 (312) 267-3455. LSR 
ENGINEERING, Box 6075. Chicago, IL 60680 



REEL TO REEL TAPES 

TRUCKLOAD sale, Ampex high quality open reel 
tape, 1800' or 2400' on 7" reels, used once, un- 
boxed. Case of 40, $45.00. Cassettes available. 
VALTECH ELECTRONICS, Box 6-RE, Richboro, 
PA 18954 



COMMUNICATIONS EQUIPMENT 

DECODE Morse, radioteletype signals frm air- 
waves with CODE*STAR reader. Kit $169.95, wired 
$229.95. Shipping $5.00. MICROCRAFT, Box 
513R, Thiensville, Wl 53092 414) 241-4654 



POWER SUPPLIES 

LABORATORY quality 5-vott, 12-volt, tri-voltage 
supply for Op-Amps, IC's, Microprocessors, Kit 
$69.95. Wired $89,95. Shipping $4.00. MICROC- 
RAFT, Box 51 3R, Thiensville, Wl 53092. (414) 241- 
8144 



PROGRAMS 



FIBEROPTICS 



ANALOG photo receiver. Beautiful sine, square, 
triangle reproduction. 10 ps response (2.0 kHz). 
Complete manual including analog LEDxmtr 
schematic. $27.50 + $2.25 P&H. Req. case and 
P.S. C. CLEARWATERS, 2074 Wallace Ave.. 
4604. Bronx, NY 10462 



ARTWORK 



ARTWORK, professional quality, fast turn around. 
Call or write today for more information or quote: 
ELECTRONIC COMMUNICATION ENG., PO Box 
18725, Greensboro, NC 27419. Phone (919) 299- 
9772 

COMPUTER PROGRAMS 

WIN $, dog race prog ram. TRS-80 I/Ill, color, pocket 
specify $25.00. PAUL PICKS, PO Box 244, Lutz, FL 
33549 



INFINITE TAX TABLE for handheld computers. 
TRS-80, Sharp, etc. Fit & Fica any amount of 
wages, dependants or pay periods. Well 
documented, including options. Send $5.95. ENER- 
GY CONTROL SYSTEMS, Box 1396, Gretna. LA 
70053 (504) 362-2090 



CB RADIO 



GET more CB channels and range! Frequency 
expanders, boosters, speech processors, FM con- 
verters, PLL/slider tricks, how-to books, plans, mod- 
ifications. Catalog $2.00. CB CITY, Box 31 500RE, 
Phoenix, AZ 85046 



Help Prevent 
Birth Defects - 
The Nation's 
Number One 
Child Health 
Problem. 

Support the 






March of 
(S) Dimes 

+ BIRTH DEFECTS 
FOUNDATION 



CO 

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59QJSURPLUS ITEMS! IBBB 



We're closing out our parts business to 
concentrate on the CompuPro line of high 
performance computers. Remaining parts listed 
below are limited quantity, first come/first served. 
Counts approximate ( + 5%). No phone orders, no 
partial orders. Use this ad as order blank, or photo- 
copy ad. 

DELUXE 1 2 V CLOCK NOW ON SPECIAL I 

For cars, vans, planes, boats, or houses using alternate DC 
power, National's MA10Q3 Is the finest looking, most readable 
12V DC clock module we've aver seen. Includes four blue/green 
fluorescent 0.3" readouts that are more pleasing to the eye, and 
more readable, than LEDs or LCDs; brightness control option; 
"dim-when-head I ights-cn" option for automotive applications; 
and sample application note. 

These have sold elsewhere for up to $19.95. Our price: S8.95 
each, 2/S17.95, or if you're looking for real value, 10/159.95! Take 
advantage now of the one of the best clock module deals on the 
market. 

CAPACITORS 

1000 UF/35V, axial 40/55 

500 uF/ISV, axial 5Q/$5 

2200 uF/16V pc mount 35/15 

1000 uFnev so/*5 

220 uF/25V pc mount 50/S5 

1000 UF/150V 25/S5 

10,000 uF/10V axial 25/S5 

TRANSISTORS 

MPS3694 NPN 1000/S35 

2N4400 NPN W leads 2000/S70 

2N5227 PNP 10OU/S35 

2N4917 PNP , , 2000/(70 

FPQ3725 quad xslstors 50/S5 



LOW PROFILE SOCKETS 

Spin 

14 pin 

16 pin , 

1Bpln , 

20 pin , , 



.50/$5 
.50/S5 

.sans 

.4045 
.36/*5 



LINEAR ICS 

LM301 30/S5 

LM741 50/J5 

LM733 50/$5 

LM380 30/SE 

LM556 25/S5 

LM703 25/S5 

UA706 20/S5 

UA723 25/S5 

Lm145S 20/S5 

CA3080 10/$5 

4195TK 20/$5 

LM7806+6reg 10/$5 

LM7808+8Vnw 1W$5 

LM7815 + 15Vreg....1tV$5 
LM781S-H8Vreg....10/$6 
LM7824 + 24V reg.... 10/S5 

LM7906-6Vreg I0/S5 

LM7908 -8V reg 10/S5 

LM7915-15Vreg 10/S5 

LM7918-18Vreg 10/S5 

LM7924 -24V reg 10/J5 



ODDS AND ENDS 

Misc. pots - some tunny shafts, some duals, some singles, no 

time to select 35/$6 

250 Ohm tri moots 50/S5 

500 Ohm 50/S5 

2£A/50Vdiode bridges 5JS5 

Dynamic mlc originally designed for Cartrfvlslon with extension 

cable (mlniplug male and female); stereo pair $5 

Extension cable as above 5/$5 



Stereo amps with LM380s and pots. May even work! . . . 



. 2/$5 



CMOS 

4010 

4015 

4016 

4019 

4022 

4023. 



40/$4 

40/15 

50/(5 

40/S5 

40/S5 

60S6 

4025 50/S5 

4028 60/$5 

4030 50/S5 

4040 20/S5 

4069 50/SS 

4071 50/S5 

4073 50/S5 

4075 50/S5 

4093 50/*5 

4116 50/S5 

4507 5u7$5 

4512 50/S5 



15 MHz crystal oscillator in small can 2/$5 

Colorburst crystal 3.58 MHz 

1 MHz HO« crystal 5/35 

OAKLAND AIRPORT, CA 94614-0355 

Send the coupon below to Bill Godbout Electronics, RE Parts 
Sale, PO Box 2356 Oakland Airport, CA 94614-0355. 



Please send the parts circled above to (PLEASE PRINT OR 
TYPE): 




Slroal Address (nsceswty lor UPS deHvary) 



Town_ 



Subtocil tor pvti: 
Cailfomnnsiddlix 
Hmdllna (alrlx* oul for orders 

Pos'aoa (al low 5** , oxcsss rtlundsd) 

TOTAL 



122 



CIRCLE 82 ON FREE INFORMATION CARD 




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124 



CIRCLE 69 ON FREE INFORMATION CARD 



r 




JE600 
Hexadecimal 
Encoder Kit 

FULLS-BtT 
LATCHED OUTPUT 
19-KEY KEYBOARD 



TITO JE60O Cncc-dar KnybDaTU Kit DfOnOK tWO lo-pararr 
hn»i"diciimal dloitt pradueacf f'om teqLeci n 1 i « I k«v *ntri-aa 
tO Allow d'lFVCT progfiTTimJnB '^ f B-bit rr^JC'OPf OtOSi-ur 
Of B-'jil mainory circuit*. TihrCtY additional V*VI * r > n r 
vldcd for Liter oparatlana wkN On* having i u.iEibln 
output wt .labia, Th«Du;nui? pra Lpich*d and moniterad 
rtUhl LEO ruooutl. Alio included iiiUvsnifv itrota. 
FaaLuFan Full fitj^t li.cheJ output far m i Crop roc* uOr 
uw. THfb« ufar-dthn* Jcryi with gnr siting bJmbl* 
a-p*raiifln. (Hbounu circuit p^vidod far an iy havs- 
9 LED raadoutt to v*rpfy *"nt r ia*. Eaiy Interfacing with 
atandi'd 10'pln IC counselor. Only +5VDC rtqoimd 
lor operation. SJJ»: 3VH * H^4"W w 8H"D 

JE600/DTE-HK .■^■'"Ji'.fSSigi ■■■■$99.95 



K19 le-Kay Keyboard {KeybDira only} ... . $14.95 

DTE-HK mi. only- whiu*"w««»"0) $44.95 



JE610 ASCII Encoded Keyboard Kit 



Trio JEG10 ASCII K*ybo«riJ Kit can bt intarfaead Into 

mOlt my cbmpu!«F iviiCm. ThB k i E CO-TIM CORiplllt 

w'ini in Industrial rjradi kayboafd iwitch iiumtny 
(fiS-kuvih IC'a, loeksn, connncTor, ttectronic compo- 
■no nii and i doubl»Hdod Drm;f{| wiring board. Th* 
krybDifd auamblv ftquJrn *&V & lSQmA and —12V 
9 10 mA for operation, Fwiuroi: SO key* ganvrat* the 
126 charactan, upp*r tin Iqwar can- ASCII "ft FuMy 
bulfarad. Two urtr-dpfinfi ka\n providad far cunto-m 
•pp tlcaito nf. CtPt lock for upp ar-caia-a nl y alpha eharac- 
icti. LrilUiat ■ 2376 (40-pln> •ncodar taad'onlv mtmorv 
chip. Output! dlractiv compatibl* wtth TTL/DTL or 
MOS logic array*. Eaiy int*rt'»ei«B with a 16-pin dip fir 
IB-pin *dga connector. Sn*. 3H"H * .4X"W : , 8VD 

JE61Q/DTE-AK ■fflff^fflg) , . .$124.96 

lp ;avc; ,'. S 7y,y& 
K62 C-Kcy Kaynoira 'Keyboard only] . . .S 34.95 
DTE'AK (uh only — 3«i"Hittl"Wid>ta ,, D)S 49.95 



JE212 - Prtoativ* 12VDC Adiptar Botrd Kit 
HlEMfH -Or JEG1Q ASCII KEYBOARD KIT Kit/ 

Provldai-lTVOCfrorn incomJngiVOC . $9.95 



JE21 5 Adjustable Dual Power Supply 

Ganaral Ducripiian: The JEZ15 is a Oust Power 
Supply with independent adjustable positive end nega- 
tive output voltages. A separate adjustment lor each 
of trie supplies provides the user unlimited applioatipns 
for IC current voltage requirements. The supply can 
also be used as a general all- purpose variable power 

Supply. FESTUHES 

- Auiuilaule reDUlaled Power lupfjlim, 
POL and mg 1.2'vDC [o 1SVDC 

• pQW«r Output taech luppJy): 
SVDCf SOOmA. 1 OV DC 4? 7 50mA, 
12VDC* 500mA, end 
15VDC4? 175mA. 

- Two, J -terminal adj. IC regulator! 
Wiin .tiermal overload protection. 

> Heat link reBuleio. eoolina 

■ LED "oo" Indicator 

• Printed B ...-. '■ Con.truc ti on 

• 12QVAC Input 

■ 5l.e: 3-U2"w k 5-1/15 ,h L x 2"H 

JEZISftdj. Dual Fnvwr Supply Kit las shownl. . $24,95 

(piciura nortnown out aimiler in construction to abovel 
JE200 Rao. Power Supply Kit 15VOC, Tamp] . . S14.95 
JE2U5 Adapter Brd.ito JE20QI *5,;9 Sr : 12V. . 512.95 
JE2IOVar.Pwr.Sply. Kil.5-15V0C.tot.6amp. . S1U.95 




Part 



5082- '650 
SO&S-76S1 
50SS-7653 
M!!-?BSB 
S08J.766O 
50BZ-7CC 

5oe;-'6o3 

50(2-7670 
5082-7671 
5082-7673 
5082-7870 
5082-7750 
5082-7751 
5082-7756 
5082-7760 



HP-Display Sale-National 

50S2 Series — 0.43 Inch — 7.Sogmimt 



CeIbi 



Hi EH fted 
HI Ell Red 

HI Ell Red 
HI Ell flea 
Yellow 
••How 
Yellow 
Green 
Green 
Green 
Green 

Bed 

Red 

Red 

Red 



Dascrlplion 



CA-LHD 
CA - RHD 
CC-RHD 
OverilowitR'HO 
C* ■ LUC- 
CA - RHD 
CC-RHO 
CA • LHD 
CA-RHD 
CC - RHD 
Overflow *1 RHD 
CA - LHD 
CA - RHD 
0verilaw±1HHD 
CC - RHfJ 



SALE 
PRICE 



1 712.49 

■;■■ 5 ;•-!-: 

4/S2.49 
t'i?t3 
4/ $2.49 
4/12.49 
47 12.49 
4/1Z49 
4/S2.49 
4/S2.49 
4/K.49 
4/12.40 
4/S2.49 
4/$2.49 
4/S2.49 



CA-Cemm. APWOe CC-Conun. Celnode LnOIPHD-LttVnglit hand dec. 



KEYBOARDS — POWER SUPPLIES 



flft"U* J ."Hi1' , H 



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U» LkH. IlKfelatiC*! tFtT twWMmf IJ.pln li-p Cbi fMM(in»l. 

Pirt Hs. XBZe $1 .95 uch K ?/».« 



MICRO SWITCH 69-KEY KEYBOARD 

LrJtti luzi PJtjtrUXJ, EiKtdai iMfUt: IK rirtM lit DIC. ItriUjMt] HM EmcL I*-pw lift 
Cart OaaaafH. EiBiH l a aO ha GmhkQh. 

Part No, KB69SD12-2 519,95 ewh 



WUNETICS T4-KEY KtYBDARD 

UCI irnraiiaf Eq-aavl, mftf*H: En* fu*| n,S£u, l*n*t n»Ut» ♦*■ -■! *f>- (ariLkag 



Pji1Hq,KB35( 



«9.95UGn 



MICRO SWITCH 35-KEY KETBOAHD 

w*« ftkhubi jtirrb-ni , n ni up c*hi chmchh . siift>rr vhui* ♦ imc. mil* t*<rt**t 

n LTWEETT. UdlOMBl Kty raA htr Can* rot mt4 pKwdao rvpcMai 

Pirl NO. B5SD1M JZ3.S5Mch 



MICflfl SWITCH 08 KEt KEVBDAflD {PARALLEL ASC.H 

Ua ISlnf KlftMrfl mi,- la a Ciaata »MD TtltXrUJ DupptT V*e>HJ« *■«, -fit. :Ix»altg Hll 
find - ifl-pa f Cgi Cvd E m id Jin . laatKitt mtmattl Uiat (HI E>»»4* Clip 

PiftNo. aasDZ2 .s&s.gsajch 



POWER SUPPLY - 5YBC @ 1 AMP HEGULATED Trahautl«tT*eli 
Dvtpiri + iVBC A 1 imp 4*>u * JtnrtiC) nr|. Iph* tSVAC UHi. Tawfa (HkUlklpI i*fr 
T -— — - g n.. 1 taaa, H**k H*-*f w«. Ik* iv, "W l r-'fr a M"H *i ] »t- 
PirtNo,PS511S4 $l9.9&«Ch 



POWER SUPPLY - 5VDC ^ 1 AMP REGULATED 



Ori.ill aWflE>. fV* V T<k"0 ( 1-/--3 "I 

PlriNo. PS4070 



B l4Mtui I ri«* 



POWER SUPPLY - 5VDC Q 7.G AHf. 1ZVBC @ 1.5 AMP SWITCHIHG 

Input: 1 1 LSVK. ES-hWj O 3 J*(V HOVAC , SOHJ O 1 -I IN. FlH nfe./fPHT lIHtT lllafl «*' 
ivit HltmWJLCl Outpul- BVK O M p-p llAC 1 i u* . > »l . Wfc. 9*-- ***■ WW* 
UfBi W'M.fe. Ilh. 
Part No, PS94V0 S49.95 BlCh 



POWER PAC - H«fl njtr Muhi-i*. B . iw Ju;^, - woe. iwdc. mvcc 

Mpirt; +imi:e»n, -hhk pii, ,.inic a 4H i +»irx ffM iwc mwm, th. 

HQViIC ]» "J,.: ± -1SS 1*1 1 m*im Blpsli 1 D USf p«.1t II p«ak [3M1 1 «H$1 Ihranrrti. 
pralKE.: 5V. +1». -IK. OHHT, PfattCrl. M. IW. a l r "H i IWVfO- M. 4* Bl. 

Pill Ho. 2S5-01B SBSaSS SJCll 



tf 



Regulated Power Supplies 

SCrTtnton's open cons! ruction (SOCj power supplies aro serfes- 
rcguloied solid-stale systems, designed to provide nq. DC 
votlages el € fovols (2-2o v/rangja), Th&ae units are operKlramed 
on sturdy black anodlzod aluminum lor excellent mounllng r 

rtATUMi; v\l/mttmK \*P* 9 H-«Hj. Un> *+**: l.SaYiu. EnV M ulau. M- 
ItAHl HR*t lot. Vflifa i^hTmI cjmM. U uhiMlOii ja< nwMm^q tgppM MIb p4 
Irti AI.C.C tun itvnM nutiUt lartmt |I*rttt F. Wlaa wmM* *tf\ 



■STL 



IlijtHiJM 



it j wM.iji.: 



IK-'U-'ll 



SV*" Minifloppy Disc Drive 

FOH TRS-K MODEL I. Ill Clndualjy Stindanj) 
Faaturai alnola or flDuttin rtcna.i1> 1 . Bt;-;o^ing 
mDda: FH aliigia. MFM dombie rjonsi|>r. 
Powa: +13VOC <tO.' — 




PowQUac Sub-Modular DC Power Supplies 

SM Serias poweF supplies include rectifying, Itltering, 
rogulating, overload end overvoltflge protedlon fundlons. You 
need only connect the sub-module to the appropriate seconder? 
transformer tap and bolt !ho unit to a healsinfc. 

REGULATION: LINE; US * i {bm tnm -10K ta * l*% |>p<i Mn UUO; .111 1BT1 MM Hi 
" bilaar » MM MlMlai H OjiiUoMl. BlrTPUT IIWJ: 1 *V "Ml, IfllV P-f 
ItHtU. INMI EHINACTEIUJTICJ. R«qyf»l " " 
15* hi iswjOvh a UHl. 





Mini Stereo^WlV 
AM/FM ^^Osi-' 



Receiver - 

WITH HESDPNOHES %ijll"|«iS 
For Joag.nl. Cycllala. I7TV 

mt.rt 4 Sports Ewe" 1 - 



FEATURES: Liflhtwelohl tisarjphones. LerfUflnW 

balance controL Full lldellty stereo sounrj. Addi- 
tional black soft carrying case & shoulder strap. Boll 
clip (hands f reel. Operates pn 3 AA cell batteries {not 
InolJ. Compact slie: 35," x 4\" x 1 ". Wt. 6 ol 



irtbl.; 



Model 2830 $29.95 



• SHIPMENT IN 24 HOURS * 



Llfillf jt\MWal3 



y^ Call: (415) 592-8097 ^wf 



JUMPER AND CABLE ASSEMBLIES 

STANDARD DIP JUMPERS 



Bel*' 


;:■■:: : 


D.I4i 


H41UH 


C.I I] 


l,-*lv. M 




tjuflau 


DIMJH 


l!*!jt Ji 


CLetajLi 


UHKM 


ftJiH 


1MI1II1 


■Mtai 


fNllt» 


DJiai 


mitui 


LT.-4. ' ■ 1 


*:■■■[■? 


0,1*1 ■* 


WHt\*V 


Aiit i in 


unnm 


tu>n 


tn-i: ia 


['Jl«.' 


IH'ljam 


OJT*l 


IHIiJSl 


E-J.-i ■ 11 


IM1MI3 


DJ143M 


13*1 3* H 


PJ?ilfl 


HIM 




































U»l 


KH1311]- 


.3 


.-. 


, j 


11 


'-II 


DWl 


«418M 


«a 






3*- 


»» 


fi-M3.i 


#3-1.132 >* 






r ■ 


:; 


Tfa 


?.-ai . il 


T> 


HT) 








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■am 


::>4;:« 


;:i 


H Jt 


<n 






»■ 


M» 


L'jaj j.j.7 


m 


an 






■ ' 


;■ 


Jin 



STANDARD DG25 SERIES CABLES 
era r < 



!TilkJJQ*HDC*,iLEa 



aiHi l DB?*p aeeiTam. 

DttH-t aim 1 DB35S lft««n. 

DSaiM-P J i*4i JD6IS* IMSaa 

DButEras «f« 1 naju' i c-aSi tTJau. 

0ILU54-4-S * IKI 7---L.Z1Z IISEiej 



S 10.00 Minimum Order — U.S, Funds Onfy 
CalHornie Residents Add ev ; % Sales Tax 
Postage — Add £% plus SJ.50 Insurance 
Sand S,A.S.£ for AfontAfy Safe Ffye/i 1 



Spec Stiools — 25C each 
Send fl&c Poalaga lor your 
FHEE 19B2 JAMECO CATALOG 

Prices Subject 10 Change 
I© 




1355 SHOREWAY ROAD t BELMONT, CA 94002 
PHONE ORDERS WELCOME — (415) 5928097 



. _ . frioM not Ind cjjvh, pOwtfi auppl; 
or catjinsj. 30-paQ4i ion Doefe inclucJe 
inda. Slza: fl WW * ("0 



.G anpa max., 
ut I 

la tigch ir^ludvd 



WtHoha 3V. potii 

P^ho, ""'"« " Pri» 

FD200 $179.95 

Shtfllt-f -4«f. «0 tracia, i»K brlf>* CapMitj 

FD2S0 S1&9.95 

Uflubl-j-tidtd. 35 tiacka, U«l. brlaa capacity 




EXPAND YOUR TRS-80 to 1BK. 32K or 4BK 

"Uddwl 1 - from *f, ta I6K Ri^itlnei i^i On= c; I 
M«J«l i - F'rwn IK ]ra *5K n^taira. f}J Tlini* Ml 
Color - F.ofn 4K to IK FtMdrac (I, On* Kii 

" ■ MAOtl 1 wjulpptd «i E>p,-ntlOn Bfiitfl Lap 10 «K C3 Two Kit* Rttq'tL 



TRS-flO 16K Conversion Kit — i 
yuunj itinui i^a lit tut Druak ui [>n^ a « 
TRS-etKl*eB0na ... 
TRSieKI'MMna. . 
TRS-UM "2»na. . 



D 



Pee Wee Boxer Fan 

* 36clm tree air delivery 

• 3.125" sq. x 1.665" depth 

- 10 yrs. cont. duty at 20 *C 
■ 115V50J60HI 

- For Apple users 



pws2ioru u ;j; 

PWS2107F >e~ 



. s 7.S5 ea. 

512.95 aa. 




Muffin® Fan 

• 105clm ireeair delivery 
M,68" sq, y 1,50" depth. 

• 10 yrs. cont. duty at 20 *C 

• Impedance protected, 
amb.ents io 70 *C 

• 115V 5QT6GHI UW Wt. 17 o*. 
S 7.95 as. 
$12,95 oh. 



MU2A14J gft!U 

MU2A1-N«.- . . . . 



y, Ww hbi - COMPUTER GRADE CAPACITORS - u nm tm 



ISO 1M 1.11 

soo m ui 

l.JM 3 .H 

1,500 IS 1.15 

],9oa » Mi 



!.5M J5 I.H 



X 3.15 

n mi 

*D Z H 
H J .H 

11 ie 

It 3 .5 
1* 4.K 

k r.» 

r) ii. 

IB Mi 

10 J » 



H.LKW ID 2.15 

:■"--- 1S l.t! 
15 1.15 



:■} (. 



7 ..» 



__ IB M4 

11, BOO 10 1.15 

u cm :u !« 

DMH II UI 

Il-,580 15 4.15 

•U.D0Q 15 5.» 

JJ.OM 10 Mi 



njm ■■' mi 

45.D*) S 9.H 

51 K0 H 5.H 

ai.DOO IS ill 

M.HO « ii", 

""" ltl 7.15 



TJ.Ii 



I 7J 



Q.'FHWa'3T>it;p. .'ALLIES A 



(ij.cso l) iK 

■B.OOfi ID 1.15 

Ji I'M 151DH 

-----2 1NH 



S4JL^J Ju$i deduct 50% ol price (fsted eboref 




JOYSTICKS 



»* sifla. 



S5 25 



, ^■»KBr S4.95 

It renv 15uK tjntjr 
v ,l JS-15 " t TlnrPe1. 



ivr an «>« l z l Vedia Cue- 



UV-EPR0M Eraser 



[flChlpa — 51 Minutes"] 



X£> 



^ 



1 1 Chip — 37 Minutw | 



Eraaaa jroa, 2716, BU, TtU, BIB, ZH2, JS&".. t=raaai up lo cMpa 

wlUlIn Si minu|»»|1 chip In 37 mlistitaij. UatnEalni cbnilanl ■ipaiur* 
diaUn.:* OF on* Inch. -Spactal Lfi-nduCtlrl roam linar al ItYilzn a la i llallC 
huildup. smiIIIIm. aafaty lock to pravanl UVaxpo«ura. Cempacl — only 
B.Ht" h 3,70' x J. CO" Complala vfith touting Iray m I nhi-j 

UVS-11EL Replacement Buib ..... .=16.95 

DE-4 UV-EPROM Eraser . . . , $ 79.95 



[V."Lt7/l"'H 1 l/a"D 



Mostek DC/DC Converter 

+5 VOLTS TO -9 VOLTS 

input ■ 5V. Q-jipuv-3V i.mgulaifidl o 30rTiA. 

PrUilad cutuH mwinitna 

DC10 SZ95ea.or2JS4.95 



%* 



Wall Transformers 
AC and DC Types 



AC25Q I "' I -U i < -i 






Pari No. 


1 nOul 


Oulpill 


r -ii - 


AC aSOlaEMWI 


nrv^oH: 


elVACTSOniA -. 


si» 


Ac «n 


11JV«0H: 


tlVACSOCfflA ... 


S4J5 


AC1DM 


■!.7K7fcOH: 


1 !VAC 1 imp 




AClfM 


11IVtS»Kr 


MAC ..Tamp 


, . tOH 


KDHH 


iirVrWHi- 


».JVAC3-Samp 


S2frS«r2Aa.*S 


ac ww 


1»V*3HI 


6VL>CUumA. .. 


?1.»Of Z/S2.« 


PCOOfl 


ISOVKiKl 


4.9.13VDC XXkriA 
B.WrJC2TBtVLA .. 




DVS4H 


llVV/rV'M: 


ll.-3Bofl^l« 


OC*» 


Mnin 


•VCCSQOiTiA ... 


. O.M 


0C13U 


iWV.'MHz 


ISVDClWmA 


UMmatPtM 



\M€>tgf3&la AM/FM Stereo 
Push Button Car Radio 




FOH VOLKSWAQEH SClWCCO, RABBIT, AUDI 50W AMD FDK 



Modal 5VW3901 $49.95^ 



m 

TJ 

H 

m 

oo 
m 

30 

_k 

to 
oo 



CIRCLE 69 ON FREE INFORMATION CARD 



125 



CPU'S & SUPPORT CHIPS 



. aw esTiAM»wi 



Jfg 33MCPU 



laMI41|*3l 



ROMs 



11 1* 3 


- ID 


ESJJ - 1 


TW54<rfcWL 


- IK 


■Hill - 4 


mm tra 


- 1 » 


Hill* - 4 


1VH-1 


, im 


nm - i. 


■WM 


- i*d 


E2S.E21 - ■ 


MK«asr r 


- m 




wren 


- <K 




IWIfl 


- Ml 


MAW - ; 


31 HAL 


- J« 




twairaji 


. AM 




n.13 


- &■> 




INTERFACE 


SHIFT 


& DRIVERS 


REGISTERS 



«1 30 



vn 



J*»rj 

I4C1I4 
HC1ST 

?4o« 

i*csn 

J4CSI) 






DOUBLE SIDED DIP RIBBON 
CABLE JUMPER ASSEMBLIES 
N4'iONG »2MJ 

NII'LOWO % i,H 

RS 232 CABLE 

10 Cortdutin*. rZZwkw coded wire, 

r<Y PVC Qutir tow, 3 'fi * dumaicr 

«p#ffi. - mn»:t».go 

Add x«i potufje for ordm unrdor 100 ' . 

Add iQ% portag*. for or/don tMt 100' . 



TRANSISTOR SPECIALS 

:■<•*:■ *<.*i.i ■■.•■. i 

H<r«ou PHCCiTn-3 

-."111 19 Tit- 14 II 

Mill tPN iwi I tHlnig PQWtP 1 1 

uhf iwci*f ritAh'SistaM nph » 

Jftfl77Hrtt9.T01 II 

jmivphs-fif i 



?t«M fPPi 5- TO 1 

>»g* in, 5. ro K 
J1.T0O* "4* Si IB If 

:«*■£« t,*t s- ro jja 

3"*i'0rlPr<r>J. tOBO 
1i"]iH*,P»»S-ro.iB 
iiPE»»X'i-?OI«l 

TIP 1 Jl FHf Si (A 

UJ[)CU 



1 II OS 

I u 



TTLIC SERIES 

J4J? ; 

?«n : 

7474 « 

?4« 4 

?4» J 

74» 



UARTt 



MPfN HEADERS .3.'»1.6tT 

24 PIN HEADERS .. . ,75 

40 PIN HEADERS . ., 1.10 

50PIN E0GEBOABD CQNN . . 3.95 

26 PIN EDGE BOARD CONN 2.SQ 

50 PIN RIGHT ANGLE CONN. - 3.95 

20 PIN RIGHT ANGLE CONN, 2.25 



SOP N R HBQN mhhje-cIQRS «JS 

10 l= H niCUOM CABLE CQHM |1H 

MINTED ClflCLJlT B0ARD 
*"• (' DOUBLE SiDE D IPQky &DARC- ■,," THICK 
tfflu 5 t? « 



SPECIALS 



soeoA 

Z9QA.. 



.S6.QQ 
. 3.75 
. 6.00 



RAM's 

2114L-4 .*t,66 

411&2 IBS 

MM3Q2 J3-2r-;<C 8.96 
33L*2? BIPOLAR 5.95 

41&*-?-&tK 11.95 

ZWJMIOt. 

STATIC 5\9& 

ANALOG DEVICES 
AD270QLDRefemnceVoiiaQfl(10V| . .* 9,96 
ADS21KO-lns(rumentatianAmp 4,95 

SPECIALS GOOD THRU SEFT, 1382 



CRT Controllers 
TM599C7NL . ..» 9.95 

TMS6B45 16.96 

TMSBZ75 T6.96 

ROM's 

2732 ..HI. 95 

2715 5,75 

DISC Controllers 

1791 ....#29.00 

1793 . . 35,00 

1796 46.00 

17$7 46.00 



7408 
7401 
7402 
74DJI 
7404 
740& 
7404 
740.T 
74Ci 
■■A-r> 
7490 
941 1 

7413 
M14 
741fl 

7417 

7430 
?*& 
74» 
7417 

7430 

ws 

7«7 
J*M 

74*3 



74U 
74K 



74» W 

?4*S U 

74W7- JJrJ 

N1TJ - 1.50 

7*121 » 

741H S 

74133 47 

J4-:".. 4* 

■?4iX 4'$ 

74146 75 

MUS. I !S 

74143 i ig 

74151 50 

7415J 40 

TSl&i l 10 

741J4 W 

74157 50 

741« m 

h«t a 

741E « 



741I& 
74117 

741 n 

74173 
Ml -4 
74175 
T4I70 

Min 

741R 

7411 1 
74113 
741W 

niti 

741M 

741S3 
.'41*4 

r4i» 

74 1H 

74157 
T43T) 

74m 

743K 
1*»t 
7436s 
74S0 

TS1M - 
«33S- 



" 



FUa WAVE BRIDGE 

PH.V _U jU 3A 



17V DC MUTTS 

TTL lilt 

S r ijga ohm , :c .* 

DP 4»»t«nM9t 



74LS SERIES 



■QXY CLASS VECTOR BOARD 



in fi' Ihlck wiTh 1 i'l 0" i{>k^ng 

4 1 ^"»;6%" $1.95 

OATEL'S DACJBEQ 

8 bit DAC-S 4.95 
CRYSTALS 

?«B I 3«M 5.0OO 80« „_ 

li.iiM U»bb. 3 571 eCW 10.CO0 ,J25 

MOB | 4 DCO EM 1«0W" 

7 WATT LD m LASER ' 

DIOPe(lR)^8 .95 

25 wan Intra Red PufM 1SG JC06 aqurv.l 
Lcuit Diode ISewcitwhi indudedi $24 35 

:n33^0PFET . . . $ .45 

2«M5JNFET t AS 

smwsUJT t .45 

EH 900 TRIGGER DIODES 441.00 

2N 5028 PROG. UJT % ,65 

DISC CAPACITORS 
IUF 16V 10'tl.OO 100, J3C0 

Ciuf 3^jV 16 11 CO Ipfl^fiJO 

IN414SIIN914) 15/1.00 

TANTALUM CAPACITORS 

22LIF 36V 6/*l,00 ]ouf jov - t JO 

68UF35V 5*1.00 jsuf 15V 3,-tl.OO 

IUFJ0V 5JJ..O0 ^ w M 

I.IUFJ0V 5/tl.OO jjup^ s M 

3.3UF20V 4,-M.OO WF20V J85 

4.7UF3SV 4J41.00 eauF,,,, „„, 

D..KFKV 3,41.00 laHJ ™ J 1 " 

2QDUFJ0V #1,75 

MINIATURE MUTLI-TURN 
TRIMMING POTS 

K. 100. IK, SDK. 60QK »-7B nch r 3/42,0g 

DIP SOCKETS 

■ PIN .17 ItflN .22 <QP1N » *lPih « 
14 PIN .30 lflPIN JZ5 2* PIN H 40PIK W 



NO. 30 WIRE WRAP WIRE 

SINGLE STRAND 1 00 . i 1 .40 



DIP SWITCHES 

CTSJl* 4 4PDSIT1DAI 135 

CTS20I 1 7*»05«TIO*H ' 40 

CTS30S 1 li*OSlT'IDN I SO 

Ct52Wl0 I0FOSIT.0N I » 



Dffl Tin 

TOGGLE SWITCHES 33» - c«T iu 



SCR's 



1.40 2 SO 
l.BD llBO 



TRIAC's 



PRV 


1A 


100 


.4b> 


20Q 


&4 


40C 


IX 


toa 


LOOT 



1 30 j 2 10 
96j3 10 

2 75]" » 



L14H-IR DETECTOR lril.00 

fP 100PHOTD TRANS '■ SO 

fl ED, YELLOW. GH EEN Of AMB Efl LARGE LED'* .2' . -.EJt 1 ,00 

MLED9QERLED... ..* .75 

MRDT4B PHOTO DAHL.XTOR *. SO 

TIL 11B0PTO ISOLATOR * j» 

IL-5 OPTO ISOLATOR ...* .46 

1 WATT ZEN ER$: 13, 4.7. 5.1. 5.B h 6-B, $.3, 9,1, 10, 
I2 r 15, IB, or 22V ....6/11.00 

20KV25OMA DIODE .§1.90 



SILICON POWER RECTIFIERS 



T*LXfi - 

74LSCI - 

MLK4 - 

74U.1& - 

741,51 1 - 

74L513 - 

74LS13 - 

7+.S14 - 

74LS1S - 

74U30 - 

74LS1] ■ 

T4L5Z! - 

74tS3t - 



74U47 - m 

'..Sil U 

74SLS5* - 3E 

T44373J - » 

74lfr« . K 

T*LS75 - J6 

74U7I - « 



fav 


1A 


3A 


t» 


50A 


125A 


240A 


100 


.« 


.14 


.35 


■SO 


4.25 


6.00 


:.j;i 


.07 


.20 


.40 


1-30 


5.35 


9.00 


403 


.09 


.25 


55 


1,50 


5.50 


12.00 


SCO 


11 


.30 


.50 


2 00 


6 50 


15.00 


eoo 


.15 


.35 


1.00 


2.50 


10.50 


16 00 


1000 


JO 


45 


I.2S 


3.00 


12.50 


26.00 



T4L1.13I - * 

7413114 - JH 

U.r.l-3 - * 

ML3TO4 - iJft 

7412.IK - a 

7*L»-» - *4 

7*UMJ » 

74L5934 - 45 

J4LS1JT - H 

'41 ^ii - si 

94LSIH - B7 

;*is - t< - -4fl 

f4h,^isj - m 

MLS1K . m 

T4L51» - K 
MUI57 - 4 
74LJ1.U - m 

Ktin - .75 

7*LSS4l ■ ?0 
74UW - 10 
5*4.1 !4J - 45 
74LSHJ4 - m 
7*J,5S» - H 
7W.SIH - i m 
!4L5>H - I 75 
74LSI70 - i # 
74LS177J - ') 
T4L1174 - : « 
74LS17I - 44 
74L5H1 - I.5B 
74L51H - tD 
74I.51IH -. -W 
JH5.-K - 71 
T4LS1KI - 72 
74U11I - 75 
74LSTH - « 
74t31H - B 



74LH*J- 
MLS3U - 
74L5741 - 

7*LSiM7 - 

74L1B1 ■ 
74LS351 ■ 
74L5S7 - 



H1.33M - 
HLSXI 

M.tW - 



74&UH - 

74tSM7 
741*5(1 - 
7K.S373 
741.5374 - 
74l«T7 - 
7413314 
744.S3B- 
744UB - 
7433M - 

74LS«n - 



LINEAR CIRCUITS 



RIBBON CABLE 

GFIAY. 2HrjT Jr jc 

SconductDT 00. ii 

* eisftdijcfcK i.D0-rr 



200 PRV 1A LASCR .95 



RS232 
CONNECTORS 

DB 25P mate $2.75 

D8 25Sfemal8 3.75 

HOODS 1.2S 



,5Vat800ma SOLAR CELLS 
3" diameter $4.35 



7 SEGMENT DISPLAYS 



FSCS024-4 dlglT 

CC B-duoJj, .15.95 

FND3» ) .75 

FWD503C.C. .5" .< .85 
DL-7W 3"C.C. ., t M 



DL-707C.A. .3". ..* 75 
FND810.a rf CA - »1-95 
FND303.8-CC 41.95 

MAN 5C.C. Gtwn 5 .75 

MAN 82 C. A. Yellow I 75 



H1.CV 

Hie 



CAXH - 

c»xm 

L.Q1Q. 



REGULATORS 

■1.7S 

J ? -^ 1LU3«-G 1 74 

I 50 " MOT 5. 5. B. 9. >2. 

330T 5.12,15m J4 I SO IS.IisrMV I t» 

;aH!M t JS L.AS14I7- 13v lA-tiSfl 



LM3I7T 
LM3I7K.. 

41S4D ... 



POSTAGE ADD lQ*fc FOR ORDERS UNDER *25.00 
HATES ADO 5% FOR ORDERS BETWEEN J25.0O AND *50,G0 

AOO 3* FOR ORDERS ABOVE *5D.0D 



TERMS FQH CAMBRIDGE MASS SEkD CHffJK SEtlO * 25 KM QUI CATJtLOG 

OA MONEY CROER MINIMUM TiLEPHrjPiE. FEAtuniNCi TAAN5.ISTOA5 Er 

COD PUFICHA5E OPOCH Ofl CHAH&E *20« PECTIFBEFL5 1 4& HAMPSmIHE 

MINJMUM MAIL CflKfi 1400 IT .CAMlFllBGl. MAIS «13* 



O 

LU 
_l 
LU 

Q 

Q 

< 

GC 

126 



SOLID STATE SALES 

P.O. BOX 74D 
SOMERVILLE, MASS. 02143 



TEL (617) 547-7053 

WE SHIP OVER 95% 

OF OUR ORDERS WITHIN 

24 HOURS OF RECEIPT 

TOLL FREE 1 -800-343-5230 

FOR ORDERS ONLY 



CIRCLE 78 ON FREE INFORMATION CARD 



SCR SUPER-BUYS 



• UHF-VHF CONVERSION KIT. 
Complete wftti PC boom, oil required com- 
pononR : cablnal wMi sown w. ond ooirpn- 
heoifes wocnun incl xavemollc lioarO kiy- 
001 mounting and hooR-op OJogrorm. ports 
list and otMtnb^ onO wt-up InstnxHonv 
ajl ports an InOjstrtol pHm* qLKillry 

• NEW ZENITH 2VM- 121 HIGH 
LEGIBILITY CRT MC+HTOH FtatuK 1 2" grew 
pno4ptof CRT. wtm 15 MKz Bondwkttti 40 
or &0 charoctvf wSdfhs ore opetotof swttcti- 
selKfable Ful^&Mnpott&lflwrlri&O -column 
Appte cords, etc 

• MITSUMI - MODEL UES-A55F 
VMACTOR UNI TUNER mfQ MHfif 

470 - B89 MH2 
My"./( AMTENNA INPUT 10 
"-/. 300 OHMS 




Our 

Own 

Fimout 

Kit 

$119.00 



Our 

Factory 

Olrtvct 

Prlca 

$117.oo 



S25.M so. 

lor $220.00 



• SPECIAL- 



2200 MFD 40 VT CAP 



-£3& 



10 tor $13.50 



• I.C. SPECIAL LM 565 10>«$16.00 

• H.D. TRANSISTORS 
SPECIALS 2 H 3055 101or$10. 

2SA 745 S4 00 to. 

2SA 747 B $4.50 60 

2SC1116B $3.25*0 

2SC1W3B $3.00 M. 

0UTSIDE CAL 800-854-8660 
INSIDE CAL (714) 527-2554 
OT (2 13) 603-9385 

ELECTRONICS INC 

VISIT OUR NEW SUPER CENTER 

5303 Lincoln Ave, Cypress, CA. 90630 

Pay by CHECK, MO, VISA, WC 

$10 00 Milt OflOSt HANDUNG/SHIFFINO $2.50 

UPS ANYWUHE IN CONT1NF*fT*L US, 



CIRCLE 96 ON FREE INFORMATION CARD 



HITECH KITS 

EOUCSTIOWIL IN NlTUItE FUN TO BUILD AND USE 



LCD Mnltlnitar 

Th*j ■rfordiblv LCD Mu I lint eta i. High aeicuriey 19 

rung.* Iirnj* 3M d'g>i DMU wiEh d.ndt ini, ui'.-a 
J £ paijrily and LO Ball ndicaLrj- F-jliy AHim&lld. 

MedW 101 .... S59.H ?V Ri'.t*-, . , . SQ.9S 



0-50V 3A Regulated 
Adjustable Power Supply 

Wiih ove'lO'Bd rnoir-licin and LED 
powar on andidHor. Aisirn SJ8-S0 
KKI T-5.03 Hit S24.M 





SOW Single Channel Power Amp, 

Compttl [ic-wer *Jltp. wslh VOlurYi« r EfoUjI* 
and tut :or.tral £xc«ll>]n| lor "iaoiiina Hi? 
power gl tqu' pnrtiols radm. o* t«uilt« 
Co^intifirci viur TV iridic iftrjeipcti*flcer.hr! 
raji idund a1 ynur TV prn-gram. 
HKIT-300 AsimS2l,95 KiLSlCM 



Pragnminible Music Door-bell 

Elec[fonredaer-tJ*M iH.nl hu 9 pfogiirnrntbla iodbe. 

Uarji CMOS ittt low pOwrff CQr»UfnptL1iri Ft fid lUI 

1U10 jhMt-CH !,'.;■,,'(■ 

HXIT-47A Aimm$l6.SO 

Kit SI 2.50 

|.gv Batt 50 95J 




7 Digit 
Universal Counter 

LJfi ivcreal CraUnlBf COUHTl up 

Ig 60 MHj and ID million 

flVBnti. 7 largo O.i" m^iis 

Cryjuat tifTW boio. High ptr- 

lurrnjnLC-. 

H KIT-SEA Kit S49.S0 




Transformers far Kits 

HK1T-S3A S7.&0 HO'IT-300 SiO.GO 
BOA £6.95 HK.IT-&03 S>1Z.IK) 



0-35V 2A Quality Power Supply 

Ptlj". idri 4 range i nl c j' m-i I !■ m> I in rj up To 2 A. 
Um prttrmn ravulatian and power tranui - 
lei bDosLe.' Aiim $24. EO 

HKIT-83A K-ib S19.E0 



Triple Output Power Supply 

+ 5vO " SArar logic mrcixi!* anO±t2Vy HA 
rOf linifl Jf clKuili i± 1 bV or ± 1 8V ii 111 ■ 

■Uo. i4?K>rv Willi ord*f| 
HKIT 115 KrlSlT.SB 

Atim S20.9B 
Trnifomwr 57,60 



Fun Clin ■ Generator 

Ganefauj urunglii. K,uar« or line 
WW* \ He lo 100 KHz. Idaal lor 
tciimg audio ampi Aiim B35 SO 
HKIT-H Kit S&.W 

To Order, und chock or rnonav order- «o 




Hitech Electronics 



442& W S«pulv«da Blvd. , Tor r aires CA 9Q505 

Phone Orders: (213) 371-2160 

VISA and. M/C wftlcomod. Minimum Orfair SB.00 
Shipping and Handling 12 00. CAi«id*nt add B>% **> 
PLEASE VISIT OUR STORE- Op-n io^W-e-00 Hon, thru s*i 

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CIRCLE 85 ON FREE INFORMATION CARD 




hee 



<WiH* 



4 



PHASOR PAIN FIELD — Patented and recently developed 
in our labs is being lesjed Oy Gov 't Tor rioi control. Soon lo come 

Wonder weapons restrictions as an internal maclime. Easily hand- 
held. Hazardous IF NOT USED WITH DISCRETION 
*j PPF- 1 PLANS [sold lor animal comrol) 11 5.00 

J INVISIBLE PAIN FIELD GENEFIATOH - Produces a dl- 
L reeiional Held or moderately intense pain lo oacK of head up to 
50'. Cigar elte pack size enclosure is easily hidden. 
I Pfi -3 PLAN S .17.00 IPG-3K KIT fi PLANS . S44.50 
•I IPG-30 (assemdlerj lor animal conlroi) S5S*.5Q 

I™ PHASOR STUNIHURNINO WAND - Produces sullicient 
eiecincal energy capable of burning llesh. Intended as a person- 
al deiertse device 
PSW-3 PLANS M.00 PSW-3K KIT & PLANS $58.50 



« 



| RUBY LASER BAY PISTOL — Intense visible red. bums, 
bazardous. with parts sources. 

RUBY PLANS (includes all pan sources) , 115.00 

CARBON DIOXIDE LASER — Generates 20-40 waits of 
continuous power capable ol burning, cuffing, hazardous. (Willi 

all part sources) $1 5.00 

LASER RIFLE — Produces 200-3000 pulses ol 30 wart opti- 
cal energy Portable and easily handheld 

LBG-3 PLANS 110.00 

LP.6-3K KIT PLANS (minus diodel J129.SQ 

POCKET LASER — For Ihe beginner, visible red "optical 
version", non-hazardous. 

LHC-2 J5.00 LHC-2K KIT & PLANS S24.50 

HIGH POWERED PORTABLE ENERGY SOURCE 
FOR LASERS AND MAGNETIC WEAPONS — Explod- 
ing wires. Shockwave, etc. Miniature size 
UPS- 1 PLAN S . . SB.00 H P5 ■ 1 K KIT & PLANS . M9.50 

PARTICLE BEAM WEAPON — PLANS ... $15.00 



INFINITY XMTR 



Uses telephone lines for selecfive home 
M or office listening while away on business or vacation 
; INF-l PUNS 



1 15.00 
SEE IN DARK — Long range, total darkness. 

WS0-4 PLANS S10.00 
„ LONG RANGE WIRELESS MIKE — Cryslal clear Quality 
~ — miniature. 

FBT-rPLANS *7.00 FBT-7KPLANS&KIT. J34.S0 

WIRELESS TELEPHONE TRANSMITTER — Long 



VWPM-5K PLANS & KIT $34.50 



range, automalic 
I VWPM-5 PLANS $10.00 



ISend for FREE catalog descriolon of above plus hundreds more 
plans, kits and completed items. We accept MC or Visa or when 
ordering , send check or money order. We pay shipping charges 
on orders over S5CI CD. otherwise induce 10% wtln remiltance. 
SEND TO: SCIENTIFIC SYSTEMS 

DEFT. R8. BOX 716. AMHERST. N.H. 03031 



CIRCLE 98 ON FREE INFORMATION CARD 

ELECTRONIC KITS FROM HAL-TRONIX 
2304 MHZ down converters, tunes in on 

CHANNELS 2 TO 7 ON YOUR OWN HOME T.V. 
HAS FREQUENCY RANGE FROM EOOO MHZ TO 
2500 UHZ. EASY TO CONSTRUCT AND COMES 
COMPLETE WITH ALL PARTS INCLUDING A 
DIE- CAST ALUM CASE AND COAX FITTINGS, 
REQUIRE A VARIABLE POWER SUPPLY AND 
ANTENNA (Antenna, can be a dish type 
or coffee can type depending on the 
signal strength in your area, ) 
2304 MOD 1 (Basic Kit) $49.95 

IllUflH L Ulltngir 

2304 MOD 2 (Basic / Pre-amp) $59.95 
2304 MOD 3 (Hi-Gain Pfe-amp) $69.95 

[rnefcjd** uh A BUtnoO 
POWER SUPPLY FOR EITHER MODEL ABOVE IS 
AVAILABLE, COMES COMPLETE WITH ALL PARTS, 
CASE. TRANSFORMER. ANTENNA SWITCH AND 
CONNECTORS (Kit) $24.95 

Assembled ...J34.95 

Slotted Microwave Antenna For Above 
Downverters $39.95 

PREAMPLIFIERS 
HAL PA-19 — 1.5 mhj to 150 mfiz. 1Mb gain operates 
on S to 16 volts at lOrna. Complete unit £8.95. 
HAL PA-1.4 — 3 mhz to 1 .4 ghi. 10 to 12 db gain oper- 
ates on 6 to 18 volts at lOma. Complete unit $12.95, 

(The above units are ideal for receivers, counters, etc.) 



IB LINE Touch tone decoder ki 



M 



12 LINE Touch tone decoder kitwith 

P.C. BOARD AND PARTS , $39. 2b 

16 LINE Encoder kit, complete with 
case, pad and components ....$39. 2b 

12 LINE Encoder kit, complete with 

CASE/ PAD AND COMPONENTS ,,,.$29. 2b 

ft***************************** 

MANY OTHER KITS AVAILABLE 



mm, 



iHFOHMATtQH, al 



Hal-Tronix 

p.q. box hoi 

Sou 1*1901 1. Ml 44193 



GlldErM GvCmsUfl <#fH,L • ( SlILPPlD KUTMjO I*CI*T 
ON ITEMl WN ERE iHDWHOHAl (M(AHi| J * PI E hecueitid 
t>U SHUtPil till )|«*hl US « *L£A*r IMCAUOE iDDHTKJ" 
' TQIt H Ml F-i 'Wfl AN0 MMLMa 1 11*13 I = 



CIRCLE 99 ON FREE INFORMATION CARD 



QUALITY parts at DISCOUNT PRICES 



4 CHANNEL 8 TRACK 
.HOME UNIT 

BRAND NEW UNITS... 
ASSEMBLY INCLUDES; 
TAPE MEAD, MOTOR BELT, 
I10VAC MOTOR, PRE-AMP, 
LIGHTS, SWITCHES, 
SOLENOID AHO OTHER 

USEFUL PARTS 

AN EXCEPTIONAL BUT! 
57.25 PER ASSEMBLY 





PRECISION 
DEVICE... 
CONTAINS "i 
S OK CENTER 
TAPPED ALPS 
POTS. $4. 75 



VARACTOR 



h-103 } FCfi j! [, 

100 FOR 550.00 

MV22O5 JFORSli0O 

100 FOR 530.00 



MITSUMI 

MODEL UES-A55 
VARACTOR UHF 




FREQ RANGE 
■•JO - 889 KHZ 

ANTEW4A INPUT 

sop cms 
$25.00 each 
lor $220.00 



MINI SIZE 
BUZZERS 

l)4l8 3»oll«75«»« 

WtTH HIRE LEADS 

ijfto 3 void 75* M 

WITH PIN TEBM1NAL5 

S. S to 7 voiti 
WITH PIN TERMINAL; 

750 each 



BLACK PLASTIC 
CASE 




BLACK PLASTIC ENCLOSURE 
ADJUSTABLE HEIGHT FROM 
1,65" TO 2.95"; WIDTH 
6,85"; DEPTH 8' 1 . BUILT- 
IN STAND OFFS FOR P.C. 
BOARDS.. FRCNT AM) BACK 
PAtCLS NOT INCLUDED.. 
S5.25 PER CASE 



PHOTO PLASH 
CAPACITORS 

170 MFD 330 VOLT 

1 1/2" X 7/8" 

2 FOR Si. 50 

10 FCfi 57. 00 

800 MFD 300 VOLT 

5 WW MICH X 1" DIA. 
51. DO EA. 10 FOR 59.00 




f 17.8Q gggjj 



AUTOMATIC 
RECORD CHANGER 

» B.S.R. MODEL C136R/C/5 

* PLAYS 5J/W78 RECORDS 

* MINI SIZE: I l/V X 12" 

INCLUDES DUST COMER WID 
"PLASTIC CASE CNOT PICTURED) 
WITH FRONT CUT OUT TO FIT 
STEREO UNIT WOT INCLUDED). 



I" HIGH 





COMPUTER 

GRADE 
CAPACITOR 

1700mM.T50VDC SZ.OC 

2 1/2" DIA X <t J/!|" HIGH 

3,600 mhi 
40VDC 51.00 

1 J/S" DIA. X J" HI 

6,400 mid. 

60VDC S2.50 

I 3/i'oia S4IN" 

12,000 mfd. 40VDC S3.00 

2" DIA X <i 1/M" HIGH 

1S,0O0mrd.75VDC S4.00 

2 1/2" DIA X <l 1/2" HIGH 

2 2.000 mfd. 15 VDC 

2"ci.X2 1tt*«,sH $2.00 

22,000 mfd.40VDC" 

2" DtA. X 6" HIGH S3.00 

25,000 mfd. 75 VOC S4^0 

5" DIA X >l 3/8" HIGH 

45, 000 mfd. 25 VDC 

2" DIA, X V HIGH $3SO 

72,000 mfd. 15 VDC 

2" DIA. X V HIGH $3,5(1 
COMPUTER CRAM 

capacitor SPECIAL 

180.000 mid. at 6V 

2^' DIA X r^" HIGH 5 1,50 
C1AMPS TO FIT CAPACrT QMS £0. ,. 



TRANSFORI 

120 vol I 
primaries 



760 MFD 330 VOLT 

2" HIGH X 1 J/r." 

51.25 EACH 10 FOR 511.00 



A=3. 



2 7/a"LG. 
Il 3/ri" TRAVEL 



Hn*ar taper 

75 t EACH 




DC WALL 

TRANSFORMER 



ALL ARE 11IVAC 

PLUG IN 



A VDC II 70 HA 
5.8 VDC It 125 MA 
9 VDC ■! 100 MA 

9 VDC II 225 HA 



12. SO 

S2.50 
5 2.00 
$3.00 



^ 



5,6 VOLTS M 750 MA t&OO 

6 VOLTS iltSDmA 1131 

12 V.C.T. It 500 mA 52 50 

IS. 5 V. it 3 AUK 5* SO 

IB VOLTS It 350 MA 12.00 

18 VOLTS .11 AMP I4.S0 

IB V.C.T. at 2 AMP 55 SO 
25.2 VCTlt 2.8 AMP 55 50 

33 V.C.T. at t AMP 53.50 

42 V.C.T. It 1.2 AMP SA.SO 

S5 V.C.I It 2 AMP 55.50 



L.E. D.'s ■ 

STANDARD JUMBO 1 
DIFFUSED 

RED 10 FCfi 51.50 
aREEM 10 FOR S2.00 [ 
YELLOW 10 FOR 52.00, 
FLASHER LID ft 

15 VOLT OPERATION 
RED JUMBO 
2 FOR SI 
■ I POLAR 
2 FOR SI 
SUB MINI LIB 



LED .^ 

RATION •» 
I SIZE J 

V't 

i in ' ■ 



RIB 



.079* X. .098 

2 0mA It 1.75 1 

10 FOR 51.00 

200 FOR SIS. 00 

QUANTITY PRICES AVAILABLE 



■ LACK LIGHT 
{ULTRAV IOLET) 
- * =!^» 

S.e. I F5T5BL $2.50 a. 



crEE! SEND FOR OUR NEW 40 PAGE CATALOG ^^ 



CONNECTORS 

WEATHERPROOF 
2 CONDUCTOR 

POLARIZED SET, II GA. 
WIRE. .51.00 / SET 

4 CONDUCTOR, 

51.50 



<& 



WEATHER-PBOOF SOCKET 
teV CONNECTOR SET... 



4PDT RELAY 

I H-JinilT.il 

"■liRfldeoflliEli 

IHrtlUcW 
• Ui«d bv. tulljr tllltl 

S1.70 EACH 

Irf*: 1 1 j C Oi I »Ql U flt 
L*JGE OLAniTlTIE!;AVJLILA BLT; 
SOCM E"TS"F'CH PELAV Mt t ■ :h 



RELAY 

T>fT*^ 



MINIATURE 

D.P.D.T. 
5 «*■ COMTACTS 
FUJU1TSU I F6R321D006 
51.75 EA ID / 16.00 



EDGE CONNECTOR 

ALL ARE .156" SPAC1H5 

15/30 GOLD 

SOLDER EYELET $2.00 EACH 

18/36 GOLD 

SOLDER EYELET 52.00 EACH 

22/44 GOLD 

SOLDERTAIL CP.C. STYLE) 
S.2. 50 EA 10 FOR 522.50 

22/44 TIN 

SOLDERTAIL CP.C, STYLED 
51.15 EA 10 FOR 512.50 

42/64 GOLD 

SOLDER EYELET Jrt.00 EACH 




CANNON xlra-3-13 75 ohm 
CONNEC 



5 PHONG 

CHASSIS MOUNT 
COWECTOR 
52.00 EACH 
10 lOr 118.00 




2" ALLIGATOR CLIPS, 

7 clips (or $1.00 
too clip* tat $12.00 
SOOellpl tor S50.00 



KEY SWITCH 

S.P.S.T. 

<t A»*>5 3 125 VAC 
KEY REMOVES BOTH 
POSITIONS 55.50 EA 




4 POSITION r, W5 

USED FOR g ,j 5 VAC 
CASH REGISTERS 
COMES MITH THREE KEYS 

11 OPERATES 2 POSITIONS 

12 OPERATES 3 POSITIONS 
• 5 OPERATES r, POSITIONS 
KEY REMOVES ONE POSITION 
ONLY 51,. 50 EACH 



LIGHT OROAN 



EASILY HOOKS INTO STEREO SPEAKERS 
AND ALLOWS 110 V.A.C. LIGHTS TO 
CKIHCE WITH MUSIC. 55.50 PER UNIT 



STRING OF 20 LIGHTS TO CONNECT TO 
EITHER CH»»B.— 51.75 FOR LIGHTS 



CfiCAN HILL SCCEPT TWO LIGHT STRINGS 



L-PAD 

STANDARD S Cttt 
SO Dfl L-PAD. 

$1.50 EA 




-frUNICORD 



8 STATION 



INTERLOCK IMG ASSEfBLY 
rt-D.P.D.T./fl-'l.P.D.T. 
6 1/2" MOUNT HE CENTERS 
55.00 PER ASSEMBLY 



S STATION 

INTERLOCKING ASSEKaLY 
J-^.P.O.T./J-D.P.D.T. 
M 1/8" MOUNTING CENTERS 
52.50 PER ASSEMBLY 

3 STATION 

NCN- INTERLOCKING 
2-0. P.O. T. /Ml. P.O. T. 
PUSH CN/PU5H OFF STYLE 
2 1/2" MOUNTING CENTERS 
51.50 PER ASSEteLY 



ROUS 

52.00 EACH 10 FOR 518.50 



MICROWAVE 
TRANSISTORS 




AX 



12 

FOOT 
R.C.X PLUGSlibTH 

ENDS.. USED FOR VIDEO 
GJfES, ETC 51.25 EA 



E 



H.P.N. SILtCON 

SPECIAL PRICE 

52.50 EACH 



O- 10 MINUTE 

ADO. TIMING 
MOTOR FROM 
- 10 MIN. 
RATEO 10 AMPS 
12S VAC MDUNT5 
CN 1" 



TIMER 



CENTERS 
71.75 EACH 




LIGHTED 
PUSH 



RED LIGHTED 120 VAC 
I 10 AMP. S.P.S.T. 
"POWER" PRINTED CN 
FACE. MOUNTS IN 
7/S" SQUARE MOLE.. 
51.50 EA 10/ 515,50 



•voH Oamp/lM 

RECHARGEABLE 



LI 



ELPCMER ( EP690 
SOLID GEL CELL 
5 1/2" X h UV 

X 2 <S/V 

515.00 EACH 



CRYSTAL] 

CASE STYLE 

HC35/U 



5 J. 50 EACH 



ALL fLfCTROMCS CORP. 



MANUFACTURERS 



WE WILL 
EXCESS 



PURCHASE YOUR 
INVENTORY (2131)380-8000 



90:> S Vermont Awe 
P O BOX i'MULi 
Lot> Angeles Cald 9UUU6 

lO. . I Hit UKUtR NO 

BOO 826-5431 

in ■■ i a 213 3SO-HOOO 

Mou. Fn Satuidav 

9 AM SPM 1JAM 3 PM 



CIRCLE 79 ON FREE INFORMATION CARD 



to 

m 

"0 

H 
m 
S. 
CD 

m 

£ 



127 



■ " i 1 FORMULA INTERNATIONAL INC. * 

V ^Jft* 12603 CRENSHAW BOULEVARD* HAWTHORNE, CALIFORNIA 90250* (213) 973-1921 ^f 




THE ' 

Pineapple 

48K Color Computer Kit 

Easy to assembly! All components are clearly silk screened on the 
circuit board. Kit includes predrilted double sided PC Board, all 
integrated circuits, sockets, professional high-impact plastic casing, 
keyboards, connectors and switching power supply. 
Features 

• Numeric key pad 

• Game paddle jacks on both sides 

• Speaker volume control on the back. 

Dealer Inquiries invited. 



5V4" Flexible Disc Sale 

Why buy other brands when you can buy MEMOREX 
disc for much less and backed by 1 year factory 

warranty. 





For Data Reliability — Memorex Flexible Discs 



PRICE BREAK-THRU ON APPLE® 

DRIVE! 

100% APPLE Compatible 

5 1 /4" Floppy Disc Drive 



$295.00 Each 
$375.00 Each 
(with controller) 




PART# DESCRIPTION 

3481 5WSSDD Soft Sector w/Hub Ring 

3483 5<V'SSDD 10 Hard Sector w/Hub Ring 

348E 5WSSDD16 Hard Sector w/Hub Ring 



3062 8" SSS D I B M Com pa t i b) e (1 28 B/S , 26 sec tors) 

3015 8"SSSD Shugart Compatible (32 Hard Sector) 

3090 8"SSDD IBM Compatible (128 B/S 26 Sectors) 

3102 8"DSDD Soft Sector (Unformatted) 

3115 8"DSDD Soft Sector (128 B/S, 26 sectors) 

3491 5V4"DSDD Soft Sector w/Hub Ring 

3493 5V4*'DSDD 10 Hard Sector w/Hub Ring 

3495 5 1 A"DSDD 16 Hard Sector w/Hub Ring 



PRICE 

1-9 $2.45 

10-99.... $2.1 5 
100-499.. $2.00 
500 & up.. call 
10pcs. 100pcs. 
$2.1 5.... $2.00 



$2.15. 
$2.85 . 
$3.30 . 
$3.50 . 
$3.25 . 
$3.25 . 
$3.25 . 



. . $2.00 
. , $2.65 
. . $3.05 
. . $3.25 
. . $3.00 
. . $3.00 
. . $3.00 



MICROPROCESSOR COMPONENTS 



Z80 8.75 Z80A-DMA . 28.50 2708 . 



Z80A 9.25 

8080A 5.50 

Z80-PIO 7.50 

Z80A-PIO. . . . 8.50 
Z80A-SIO... 29.50 
Z80A-CTC ... 8.50 



2102 1.50 

21L02 1.50 

2114 2.95 

2114L. 2.95 

4116 3.00 

1702A 4.95 



2716.., 
2516... 
2732 . . , 
2532 . . . 
2764 49.95 



. 5.95 
.9.60 
11.95 
15.95 
16.95 



MONITORS 

MODEL NO. DESCRIPTION LIST SALE 

VM4509 9" B&W, 10 MHz $190.00 $169.00 

DM 5109 9" Green, 10 MHz $200.00 $180.00 

DM 8012 12" B&W, 18MHz $250.00 $225.00 

DM8112 12" Green, 18MHz $260.00 $235.00 

DMC6013 13" Color $470.00 $425.00 

DMC6113 13" RGB Color $995.00 $895.00 



IC SOCKETS 

LP WW LP WW 

8-pin 5/ .75 5/1.91 22-pin 5/1.62 5/4.66 

14-pin 5/1.00 5/2.40 24-pin 5/1.80 5/4.77 

16-pin 5/1.20 5/2.65 28-pin 5/2.10 5/5.87 

18-pin 5/1.35 5/2.98 40-pin 5/3.02 5/6.89 

20-pin 5/1.52 5/4.55 



SPECIAL OF THE MONTH 

2532EPROM 4116{200nS) 2732 EPROM 

$9.95 ea. 8/$13.50 32/$43.20 $8.95 ea. 

LIMITED QUANTITY 



CIRCLE 70 ON FREE INFORMATION CARD 



Or FORMULA INTERNATIONAL INC. % 

"" »ilV 12603 CRENSHAW BOULEVARD • HAWTHORNE CALIFORNIA 90250 • (213) 973-1921 



MATCHED PAIR POWER TRANSISTORS 

BV MOTOROLA 

A MJJ9S5 FNP 150vYiiii Bl'aW $3.50 

A 2NM55 NPM r SO Wall* IC="lSA p, ppir 

B. f.' .1 .!:"![,[. PNP »Wfm IIV^EGV $3.00 

B MJE3C55 NPN 90 Wilts IC=10A pet pair 

C MJ1&DQ3 NPK 2MWiiu BV=*>40V $12.00 

C MJlHKW PIVP 250 Wall* K>=?GA (Hrnam- 

All above parti guaranteed prim* and include data sheets 




HYBRID AUDIO POWER AMPLIFIER IC'i 

From 7 WATTS Id 1 00 WATTS 

Typrcal ratings- CpvrsEincj •.,-,- ismp BS'C. THD=0 5V 

=20Hi-ttKHj.trtpuLrri<«t*flr*Po=Q tW30Kfl Power band 
whdlh?Wl-SO*;^I Ffeq resume 1 0-1 OOttHLt Output 'fid- 
t*nee =30(1. Wiiti bullion protecTion circus, Alt urnu cams 
■with dili iheel 



Pan No 


Output 


VCC 


Unit Price 


5TK04Q 


JOW+lOW 


±I6V 


614.60' 


$TKQ4I 


H5W+15W 


±20V 


SIS. 50 


51K.05O 


SOW 


±35V 


$26.50 


STK054 


23W 


±I9V 


S13.50 


STttO&o 


30W 


±22V 


S18.50 


STK070 


70W 


±42V 


$32.50 


■oTJWI 5 


TW+TW 


30V 


$ 8.50 


STK439 


15W4-ISW 


39. 


SIS CD 


STkJoS 


30W+-30W 


ttBV 


$25,50 


5TK01Q5 


lOOW 


±5DV 


$30.50 



SANYO ANTENNA SIGNAL BOOSTER 

Th;( Booster lJ ip*Ci ally des rjned for LTH F Chmndi 1 1 * -B3l. 
Aft*, r i.i n a il injj ijb-q-t ween the antenna input c ahta antf [he UH f 
tonerf. Ihil Unit will rjrrovidt I *n>n*mum 0? lOdB gam that I 
approianAiciy 2 lames belter thin you jr* sc*mg now Ideal 
far that* who live m ipuirntnu thit cja not put «-p in our- 

tfMijnHnhjSmi|i.ns.Jfar! T : l1H r 1 " Supply voltage 

<s l&VDC Back In Stock 




■■ * w V 



SANYO UHFVARACTOR TUNER 

FOhVUHF CHANNEL 14-83 
Tunrno voltage +1 -+28VDC Inpul impedance JSfi IF bind 
widlttT-lfiMHi Ntu%* figure 1 I MB M»i Sua 2H x VA k 

k Supply voltage 15VDC Sound if^SSOMh^ 
Model 1 1O-B-403A Video JF 45.0MH. 
Modal 1 I E-B'+Q&A, Video If 62 %Mrl ( 

$36.00 •* 

funef is the most imporTantpad nHh* circuit Du- - r- those 
S'SOQlunsrslool you 

4'.i units jii brand f>B* born S»n T p When orating please 
loecify mode I number 



No FCC License 

Required 

OUR PRICE 

$49 50 
ADDITIONAL 

MICROPHONE 
iTFfANSMlTTEflj 

AVAILABLE 
AT 828.00 fACit 



CRYSTAL CONTROLLED 

WIRELESS MICROPHONE 

SYSTEM 



Transmitter FET mic lot "In 

30-is xhj mparn* xui 

controtlcrd 49 MH'/ Ml Dsn(l 

inr dri)t-Ir<fl pfiriprmanH 100 

MW aw I'fKil h ingt jpflroj. 

H rrutfll lor IrtiiAlfr D&ng, 

rJiFtfjp lr<nimii- 

aion Powrted m a 

9V 'idio Eu[»ry ' a- 



Rtclwnr XtldtOfl- 

MURA «MHS troll*) Ig^l on 49 

MMjT 'rar*smill*[ i-nnil On pinq- VU fTielc' nsi,ftsin.'i thA 
Itgnal lUflftgtK Ftam. Ehl micipphone SssnrJtrd phon* jKk 
(iu(lHl c.Tvntc^iian (□ i PA -i Other purine lOQuL 9V Oallery 
incliMjott Thu prolD4»ional ivt n. ideal lor on iljfjt. in fielO, 
Church, m 'iqus* V ouTdoor uu 



PHONEORDERSONLY 
CALL TOLL FREE 
1-800-672-8758 




WHISTLE ACTIVATED SWITCH BOARD 

AH bOlfdl air [im-mrmmn! jnrj tnled Your whllltff ID lit 
FET conrjenicr nrui; ropfwrm Irom a diaujncq.^i for a\ 30 'eet 
■way iinaniUfrirv can bet eaiiiy adivtEid). wJI [urn ihe swjtch 
on and it you whmlv agjiui. ii will ivm oH Idval tot nmois 
control Erjyi. tiltiiir.cal appliance iuch it Itcjhli coH»» potf . 
TV. Hi-Fn. rxlio. «r Other cwoibcI f Urul WOAl on 9VDC 

MODFL R6R $4.60**. 




PROFESSIONAL REGULATED 
VARIABLE DC POWER SUPPLY KIT 



At: tolid Halt circuitry with high etTiciancy po»«j trinit-itor 
^S03SS inri IC voitogs regulator MCI 733. Ourpji volliQ« 
can be ad(u.itrH 'ram 0'30V it 1A Current l>miledi dl'Q-1 5V il 
2A cmFant hrnned Ihtemal rniiUnc* n leit ihjm COSfl 
ripple and n-oiif \m [han lfllV dual ofi panel melcn Tpr 
veiugr and amp leading, alio wn h on bond LEO and audible 
crxer load indicaior. Kn co-nei wiih pngndnlled PC Boirct 
inlln^liona all neceffinf • lectin Hi CORipenentL Iraniloi. 
•nil rod a piofotlional looking malal c^hi^f I Thn besi pro- 
|*H F«r ichool and lh* Troll useful antUumeflE lOr repairmen 
HuUdOnr lodaf 

MODEL TBABA CM5VDC * 2A 

MOD E L TRfflB 0-3QV&C 9 1 A 



SS9.50 P*r KJI 




TABOO 
120WPUREDC POWER STEREO AMP KIT 

Gesinip power hu-ngry Tiom yotir srnill amp' H*v€ to waieh 
your bud>rjtr'Here'»a fjoodioiuEioni Thn TA-HODiaapuffiOC 
amphriar w.lh a tn.11 in pre'imp Alt coupling CudaCiEOn are 
ahmirialiiiJ ro give you a true rtprrjdireticin or the muiJt On 
board tone md volume cont'ott coWhina-d w>ih butii m p>pwer 
Mpplqr waM i»i TA'&OO lira moil campac e i;«r*o amp avtil- 
ebl« SpeciriCitiOAi gov.-. 3 -n-c^-H Frcq rengeO-iOOKHf 
±3dS THD 01* ev better Solatia TOdB SantilrviEv 3mV 
m id 47H Power Rtqutwmen t; ±24-fl0 V&lti 
A GOOD BUT 
•t $66.00 

SUPER FM WIRELESS MIC KIT — MARK III 

Thn nnw dengmed Chtcuii uirs high Ffl c C FET uanantora 
withflfagapra-amp Tringmiti FM nngc rSH- 1 20MHj! up 
to 2 Mocfcl away end wuh ih» y\ua unailhioeondentBr mic- 
roohOKfl. 1hlt com* 1 Wrl h Ihe kiE, all ow i ynu 14 pick up any 
iQund wiihm C& Fi «wjy Km mciudei tu aiecuonic pan* 
OSC Ctiili. n-d PC Board Power lopply 9VOC: 

FMC-lOS 
$11.50 Per Kit 

ULTRASONIC SWITCH KIT 

KH include! th* Ullra Sonic Tian&ducen 2 PC Boards loi 
na ram i in* and receiver, «li >i«cin>nic pand »nrJ imtrucEioni 
Ea»y io build and a\ lot el uki iuch, pi rc-mola conirol Tor 
TV. garage door, itarni lyitem or counier LTnn operaiei 
hyg-IJVDC SIS.SOo*. 



ELECTRONIC SWITCH KIT 

CONDENSER TYPE Tcigch On-Touch 011 Ui*» JaTSt.C 

and l2Vretay $6 50 




LOWTIM DC STEREO PRE AMP KITTA- 1020 

-porateiL Ewand.^ew OC fit Jigt Hi il gives a linquen c> in 
pent* Irtun 0-lOOKhf ±0 MB Addctd lealurci irke (on* de- 

anej Ipui7n«* tpnliftl \o\ vchj rattor your own Irequancr 
supplies ro eliminate pcnvir riuctuitdon 1 
SpMilm iliona *THt)/TlW less i had D05't, ■ Frsqueney 
responiq OC IO >00KHv ±0 S?dB • HlAA deviation ±0 3dB 

• SflK rano better imn* JTjdD •SflnnmnEy PMantjJmVITK/ 
Ave iilOmv 1Q0K •OuHdue lev«1 1 3V ■ Wa\ putpui IBV 

• Tone conlipols Bf is ± I C* fl ^ e,(Jm ,. ■ t rrr t.le ±1 OdS <J 1 'SHj- 

• Power suppdy ±24vTl)C •* 0.5A Hit rvnti with recpuJftled 
power uopty. ell «w need hi • 4&VCT i.innilnm»»r I* iA 



Only $44.50 
KTormtr 
54 50 ea 



Power Tran»fcirm"«r 

124.00 ». 



it* 



1 MW CLASS A POWER AMP KIT 

Dyrtemir; Bias C'ns "A" CUCint design malf s 1 hi-j «m: unique 
m its clan. Cficiiil clvar. 10Q wan* power ouicut will lanahr 
ihe moil picky f*m A periectcctmpinaiipn with ihe TA-S02O 
Jow TIM sieiei> ore-amp 

Sp«if iciuont- • riiipui power 1 0OW fiM £ mEO BR 1 25W 
RMS into an * Frtqutmcy responif IOKz-IOOKHj • rUD 
leu iFtin O.OOftH * S/N ral« bfllT*r ihan QOdB * Input len- 
silrvHy >Vmu. * Power *uppry ±40v 9 SA 



T WATT AUDIO AMP 

AH pans *n pca-asiembled on a mini PC Board!. S-upph 
Voltage S-9V0C 

SPECIAL PR tCE $1,95 



6W AUDIO AMP KIT 

ilh Vnlump [?m.!rol Pqw^r Supply 4 I 8VCR 
Only ST.50 



TA423 60 WATTS TOTAL 
30W + 30W STEREO AMP KIT 

1 hi i is a =ohd stale ill iransistorcircuiiry vyjih on bond tic 1 1 o 
pre-Errnp lor rnOll microphone or phpne input. Power output 
employi 2 pain flsiicFung OarlnngEon trammors driven o v 
The papular .7N3Q&3 Drrvpr Tmrnistpn Four brillT on board 
control* lor, velum*, balance, ireblv and bau Power supply 
requires 48YCT 2 5A ir j nilarmn THDol teii ihin 0.1 »b»t- 
ween lOGRj-TOKh* ai full powej [30 Wettq -r- 3X> WitU 
loaded mio Ml\ 



♦ SPECIAL* 

EXCELLENT PRICEi 

M00EL001-003a 

$29 50 per Kit 

"r.i i.-j !.i: "-i r : 

510.50 ae. 




ELECTRONIC DUAL SPEAKER PROTECTOR 

Cuts oh" when circu it is ihorted or oyar leaded to protect ye-ur 
amplifier ai well ai your ip**fctra, A must 'a- OCL circuits 

KIT FORM $fl,7& OB. 

"FISHER" 30 WATT STEREO AMP 
MAIN AMP |15W a 2) Kd mciudei 2 pc*. FejlMr PA 301 

Hybrid 1 10, all ftleclrcinlc parts with PC Board. Pdwii Supply 

±16VDC (np| included). Power band wuh iKF Htt3dfii 

Voliage gam 33dB Z0H*-20KHf, 

5 up c r Buy 

Only S1B.50 

FLUORESCENT AUDIO LEVEL MONITOR 

this is ihe kind of VL, monitor ihet is bting uiad by tnoii 
implilier nunulsrLurers ict are triad lo umplily circuit 
layout Easy io assemble and can be used wiili all power 
level smptiliers Power requirement 12VDC 



TE-221 HIT 

For Just 528. 50 

l inn fil Stock| 




MARK IV— 15 STEP 
LED POWER LEVEL INDICATOR KIT 

Thn neiu stereo l-eveii indicaEO^ kit coaihis ol 3B4 'color LEOa 
rib per channel] 1o mdicale lUe sound level nilput ol your 
amfjiilini Irom -3QdB to +3dB Comri with a weiL dcsioned 
sits screen printed plastic parcel and has a selector swilch to 
allow Ho ilirig di- gradual OUlflUt indicating Power supply is 6- 
1 2V0Cwtlh THG on board input sensilinilTContrpl's Tliisuml 
can wort with any amplifier torn I W to 3O0WI K-t includes 
TD pes dtrftv iranseslpi). 38 PCs mUclHo 4-ColOf LF-Di dill 
other ehTclronK componems, PC Board and fmni panel 
MARK (V KIT 
$31.50 



E83ISHSHES 



RFGULATEO DUAL VOLTAGE SUPPLY KIT 

± 1030 VDC ^ 250 ma adju amble. Fully reg. 
ulatod. Kit includes all Blecl«inic parti, Hilar 
capacitors. iC's. hone sinks and PC Board. 
J12.S0 par k 1 1 




AUDIO FHEOUENCY SPECTRUM 
ANALYSER KIT TA-2900 

This Avd'D F'«|-L*ncjf SpMlmrn An»1yier analys*t audn-i 
iNjnais in 10 us,u*e: oyei a dynamo tinge of 30 dB The 
techn-oue sMowi the sound coloration' m1toduc«o py 
uhwi^rt-d rotim and ipeaker rescmancrjs lo tw lubitannaiiy 



Th* TA'JSSG 1 provrtl«. m vn.ual pr*sunr*tTin o* 1he tnanging. 
spectrum ihru 1QQ n4 LEO displays So ■/&•/ cm Kiualty 
ice proor of tfi* equalled sound you^e achietcd The 
TA'2900 kU comes yntn all the fletiromc tampanenii 
I C pied i. lieu PC board the inii,uf.i,ons and a IgP flj C ^ 
Wouni type m*ii.i cabmei tvith pialras.rjnrii wtUcrMn 
prinle-fl h rant panel 
Specil-calions 

• input Stnsitiiity Tap* Mevnitof lOmV - r gmv 50K Onmi 

Speaker Terminal 2W ■ iOOW J C*wris 

- Display L*vet A*ng* i a ■ raciiMest Zoli per ftep - taoB 
K>*dB 

• DcHy Time 1 1 «Bbri Fast lictB s Slow &3 B i 

- Ppvvt" Inpul ll^Vor 2JOV ACMSOHi 

• Pow*. Coniumphon jflyy 

"■ Oimemaionj *e2*wi. ■ 1C?,H1 ■ S5Q[D] mm 
$99.50 par Ml 



POWER SUPPLY KiT 

0>3OVrx: AEIjULATED Uses UA723 and 1 2N30&5 power 

tramiisjor Output can be ed|usterj Irom 0-30V It ZA Com- 

p'ele wrth PC Doard and all electronic pans 

TRANSFORM^ R $9.50 w 

POwEfl SUPPLY kit $10.50 en 



PROFESSIONAL FM WIRELESS 

MICROPHONE 
Madft by one o! Ihfl leading jduana-ae manu'ac' 
turers. Thk5 lactory assembled FM wirelsss 
mlciophorie is powered by two aa $■#& batierl&s. 
IE trans mils In 1he range ol 88-108 MHz, Etrjment 
ii built in a piastre lube iype case with an omn,- 
direcElarLal alec Ironic condonsor mJcfopnone unil. 
By using a standard FM radio, signal can ba h*ardi 
arywhore an e one -acre lav Soun:J qua Illy was 
(udflefl "very flood," MODEL WEM-3fj. 
WAS S 16.50 
ON SALE 
S12.50 each 




Never v«iorry sbDUt baiiery. bacauie it has nanel Eaiy ID cury in 
pockei and bandy lo use iobji lor emergency hghE. Ii genm- 
iies IIS own elBCtriClly by soueeung grip rrjver P>t»tone m your 
Ear. boat camper oi home You may need n some time' 
EXCLUSIVE $3.95 *a 

FLUORESCENT LIGHT DHIVER KIT 
12V DC POWERED Llpltli up fl-1 h Wait Flu rMesee-hl Lighi 
TuEms idcsi for cjimpei. outdoor j.uio ai boat Kit include! 
high voltage eo-l. pOwei Iraniialor heal link, a\t other elec- 
nomc pffii and PC Boa<-d Light [u-be noi <ncluded 
$B50 Piw Kit 

SOLAR CELLS 
BV 200MA Ideal lor nil k-nds of tcdji proiecls ceils can be 

put in semes to dobbin VOltBOE Or pd'aHe-l TO double current 

$1 99 as, 



FOR COMMERCi AL FBEE TV B OX BUILDERS 



MC13S8. 


. 5J CO S3 


LM3M ... S?.O0»a 


M0135Q. 

MCl.-fV 


. . 5; : ! r= a*. 

saco« 




LM7B18 ■:■.;■■ 


MC149S. 


. J2.50 « 


tOKlOTP.C. fnounl &00«a. 


^01458- 


.. 11.00 49. 


rOK1T P.O. Mos.nl S ,.75 «* 


.MIBfl?. 


13 7S ea. 


Toxmd Coils (Sot or *]..- 13 00 ea 


u Ei«5... 


. SJ.lfl u 


5'35pF fTiimm#rCap) .65 «* 


NEJ44. . 


■ , » 45 el 


Pow*r TrarBtormar Ifly.BAH^ ft* 



NEW ARRIVALS 
6-WAY A/C ADAPTOR 

InpuL nov Art; Outpul: 3v, 4.5V. 6v. 7.5v i 12vDC 
Current: MOitiA 

OUR LOW PRICE 
SS.50 each 

19" RACK MOUNT CABINETS 

Black anoritzed front panal wien black textured 
case. 



WIDTH 
IT" 



DEPTH 

1H4" 
11 V4" 
11V4" 



HEIGHT 
3" 
5" 



125 50 
(31.60 
$39 50 



Minimum Ordar 110.00 f Calif. RntcHmls add G.E% 
Salai Tan, Phcwr* Ord*ri Accarplad on VISA or MC 
ONLY, NO COD. 4 !. Plica, aubfacl lo ehancjp 



CIRCLE 70 ON FREE INFORMATION CARD 



z 
o 

DC 

r- 
O 



Brand New Micro Computer 
Power Supply 



" Swilching regulation 

* Multiple DC outputs; 
+ 5V4A -1£V 1A 

+ 12V1A -2.2IO1SV0.5A 

* Fiberglass PCB 

' Over-voltage protection wilti IC monitor 
•110'22DV input 
' Factory assembled 

* Circuit diagram available 

(for a copy, send sell-addressed stamped 
envelops) 
" $49.00 each, freight prepaid 
(C&lil residents pis add S3 sales tax) 




Model A501 Power Amp 
' Pure Class A 25W + 2SW 

■ Switchable to Class AB 100W f 100W 

' Switchable to Bridge Class A 100W mono 

• Switchable to Bridge Class AB 300VV mono 

• Frequency Response 5-200KHz (-idB) 

■ Slgnal-to-Noise Ratio 120dB 

* Non-magnetic Chassis 

* "Out-board" comprehensive protection 
circuitry 

' DC circuitry with limited use of NFB 
High Efficiency Fluid Convection Coolinq 
"^ under 0,007% 




$299.00 



FUJITECH AUDIO KITS 



LATEST AUDIO TECHNOLOGY 
FROM JAPAN 

Send $5.00 for each assembly manual, 

refundable with order. 

Monarchy Engineering, Inc. 
380 Swift Avenue, Unit 21 
South San Francisco, CA 94080 

Visa or Mastercharge acceptable. 



Model A502 DC Stereo Control Center 

' Direct DC coupling from Input to Output 

' DC servo circuitry 

' Cascade FET Input in all stages 

' Separate Moving Coil RIAA amplifier 

' Distortion below 0.005% (3V) 

' Max Output 15V 

* Frequency Response 20Hz-20KHz ±0.2 dB 

* Maximum Phono Input 

MC = 16mv RMS (1KHz) 
MM = 270mv RMS (1KHz) 

* Built-in Headphone amplifier „_ _„, „ 

* Relay Output Muting KIT ONLY 

M $349.00 




$349.00 



B. G. MICRO 



9. 0. Box 280298 Dallas. Tanas 75228 
(214) 271-5546 

Vlt* • MttftrCird • Amur I tan Expfa*i 



STATIC HAM 



21L02-1KX1 250 n.l. 

Low Power 

2114L-3 1KX4 300 n.A. 

Low Power 2.T5 8/17.50 

KH6I1SP.4-2KX8 .Sn-zOO n.t. 

CMOS Low Powtr 271B 

aryir Pin Out S 55.95 

TMM20t6-2K>t8 •Sy-NKOS. 

200 n.1. - 371« Slyk 

Pin Out 6 59 95 

€501-5 2S6X4 - CMOS - Ojua 

Haltntlon 2 Vol(» - 13 Plo - 200 n,t. 

Tvp. 5V Vary Low Pow«r 1.50 

8514 J-5 1KX4-CMOS Super Low 

Ppwtr 350 n.t. Similar to 2114 

Sam* Pin Oul 2.95 

B10B-5 IKKS MHOS 5V S00 MS 

22 Pin 2-50 



SOCKETS 

Low Profile Solder 

B Pin 13/1.00 

14 Pin 10/1.00 

16 Pin 8/1.00 

18 Pin 8/1.00 

20 Pin 7/1.00 

24 Pin 6/1.00 

28 Pin 6/1.00 

40 Pin 5/1.00 

Buy S10 Get S1.00 
FREE CHOICE 



4K STATIC RAMS 
LESS THAN 9« EACH 
MK4A04J-4 - 250 N.S. 11 Pin Ceramic 
Coflipulflf Mfg. Surplus PRIME, Fu% 
Sialic tuf to LrttJ. Hart Same Pin Out a? 
TM-S4044, bul illghHy dllfare.il liming. 
With Sp*«- (Moitek) 

5 tor 6.95 32 lor 29.35 
VERT LOW POWERS 



DYNAMIC RAM 



528DN-5 (21OTB-4 ■ TMS4060) 

4KX1 72 Pin 8/3.95 

4027-4KX1-250 n.I 1.75 

4116-16KX1-200n.f 8/14.95 

4164- +SV 64K . . . 12.»5 8/79.95 



PRECISION HYBRID 
OSCILLATOR MODULE 



KM bom 1 MHZ and 2 MHZ TTL - ouipult - 

Hirnnilcij;^ lcil.d — un.a high ttabllLty ov«r 
n-ld. tamp, ring* — originally ehi mat S4Q.QO 
tach — wt mad* ■ Hipif purchasa 1fom ■ major 
conipular mjnulKlurar — 5 Volt optrttkjn — lit, 
tundard 24 pin tocktt — Mtnuiaeturad by 
Mgtoioja onlllalef dlmlon . . . . 7.50 (w/datt) 
MCG671 A 3/20-00 



8035 .... 
8039 .... 

0748 Intel 



. 6.95 
. 7.95 
15.95 



LSOO 

LS02 

LS04 

LS0S 

LS08 

LS10 

LS14 

LS20 

LS27 

LSOO 

LS02 

LS42 

L574 

LSS5 

LS86 

LS90 

LSI 09 

LS123 



.24 
24 

.24 
.2.1 
.24 
J4 
.89 
.14 

.24 
.36 
.-•.9 
44 
.95 
.39 
.63 
.39 
.93 



LS125 
LS13S 
LS139 
LSI 51 
LSI 53 
LSI 54 
LS187 
LS161 
LS164 
LSI is 
LS175 
LS181 
LS192 
LS193 
LS221 
LS240 
LS241 
LS242 



.95 LS2.-.2 
79 LS244 
.79 LS24S 
.79 LS257 
.79 LS266 
LS2B3 
LS290 
LS293 
LS258 
LS367 
LS36S 
LS373 
LS374 
LS375 
LS377 
LS390 
LS393 
LS399 



1.7S 
.79 
*9 

.99 
.99 
.39 

1.99 
.99 
.99 

1.10 
.99 
.99 

1.49 



1.49 
.99 
1.95 
.79 
.59 
.99 
.99 
1.7S 
.89 
.79 
.79 
.99 
1.49 
1.19 
1.49 
1.19 
1.19 
.99 



MISCELLANEOUS 



AYlMSlQ-Sourid Chip wilt. H 

page data manual 

DM9131 6 Bll Unified But 

Comparator 

8 Pin Qjp Shunl 



EPROM 



. 2.99 

371.00 



YftMoamjwTnMB 

AT5.1013 

IA*5402. + 5v High tp«*d 
UABT-AYS-1013 pin QUI 



MCH00L5 D lo A Con«.n«r 

a Bit 

AOSG1J to A Cornirur 

10 Bit 



3-00 
1.79 



170IA 25SXa till 2JSS 

270» IKXt 450 ru. 2JE 

27A0S IKXB 350 n> MS 



2715 2KX5+5V 450 n.t 5.95 

(Bur ; e»i 1 free.) 



1771 Singli Dtntlly FDC 

1791 Double Den illy FDC 29.95 

5027-CRT Conlrolltr - 

Proertmm&blt . 24 K B0 14.95 

ESB45 - Molorolt (HD46S05SP) 

CRT Controller 1759 



S2S123.33XS Trl Stilt Bl polti 

PROM 

32S129 Trl sit to 91 Polar Prom 



1.39 
1.99 



271S-1 2KXS->Sv3S0 n.t 7.SS 

2732 4KX9 450 n.t. Inltl Pin Oul (AS 

2732A-3 4K l B 350 n J. 

Inlci Pin Out Low Powtf 11.95 

2532 *KXfl 450 n.t. T.I. Pin Oul 9.95 



Z80 2.5 HI1ZCPU .1.35 

ZBOOMA-DMA Conlrolltr 9.95 

Z60PIO - PiralW S.95 

ZftOSJO/O Chin. S«r. 16.95 

ZBOA^MHZ CPU . , fl.95 

ZBOASIO/O 19.95 



O 
5 
< 

cr 
130 



CA LL OR WRITE FOR PRICES ON CMOS-8080 

,BHB ' 



74S - CRYSTALS - DIP SWITCHES 




CABLE TV 



CONVERTERS 
DESCRAMBLERS 

Largest Selection 
of Equipment Available 

$Buy Warehouse Direct & Save $ 



*> 



36 channel 
converter 

$4595 




36 channel 

wired remote 

converter 

only 

$8895 



Send $2 for complete catalog 
of converters and unscramblers 

Quanlily Discount* * Visa * Muster Charge 
Add ?*'$ shipping — Mich, rnidcnls add 4 D '« lales lax 



C&D Electronics, Inc. 

P.O. Box 21, Jettison, MI 49428 
(616) 669-2440 



CIRCLE 89 ON FREE INFORMATION CARD 



MICROWAVE EQUIPMENT 

IHI-SAIX, LOU HCI5E, 2.1-2.4ShI. 
' MICROWAVE RECEIVING SYSTEM 
i COMPLETE —READY TO INSTALL. 
1 INCLUDES t0' PARACOLIC ANTENNA, 
JuOVN CONVERTER. P0VER SUPPLY, 
'ALL CABLES AND CONNECTORS WITH 
COMPLETE INSTRUCTIONS FOR EAST 
INSTALLATION. 
COMPLETE SYSTEM -U.S. SHIPPING FREE- $119 
BUY S SYSTEMS at JI04 each 
{six Month Huttoo warranty) 




SUPER LED's 



tamp, rating w/heat sink 
ME2 IR fa] 25A pulse 




ME5 IR .b $. ._ , °$ 



RESISTOR SALE 

J5W 5% carbon film. $1.50 per 100 {one value) 
all itDndari! values from % 12 per 1000 
1.7 to 4.7M ohm: 



SOeS NEC CEtAHIC «0 PIR jtlCBOPSOCESSOR (S.95 

NH5290J NSC lGKxl DYRAMIC RAH M1I6) CEEANIC 2.JS 

B27S8 INTEL EPR0H IK18 24 PIR CERAMIC 3.9S 

TRIAC RCA S ANP «00V T0-22O TAB CASE IS 

VOX VOICE ACTUATED SU. (SCR.MICAHP . ) .95 

M11A-2 S.E. 0PTO ISOLATOR « PIK DIP 2S 

S191 25CI4 CMOS RANDOM ACCESS MEMORY DIP 95 

TRIAC 25 ANP 400V OH 3"x6" ALUHINUHS MS J.9S 

7402 Til OUAO 2 IH tfOR GATE DIP 10 

74S0 TTL 9 INPUT HAND SATE DIP 10 

7440 TTL DUAL 4 INPUT BUFFER DIP 10 

TO-92 PHP TRANSISTOR PAK 1D0 PRIME FOR 5.00 

LN747 DUAL 741 OPERATI0RAL AHPLIFIER 0IP SO 

LH0C21 NSC 1 AHP OPEflATIONAL AMPLIFIER T03 5 00 

J504T 1024 BIT DYNAMIC SHIFT REGISTER TO-5 1 00 

2416 IHTEL 256x24 CHARGE COUPLED MEMORY 2 50 

5244 IHTEL DRIVER FDR ABOVE MEMORY 2 50 
1ZP1B/1S DC TO 0C CONVERTER- 12VDC TO DUAL 
1SV AT 40MA OUTPUT, CAR BE PLUS 
OR NIHUS IS OR 30V 24 PIN DIP 



4811 MYRTLE AVE 

PO BOX 41778 
Sacramento, Ca, 

95841 



7.95; 



w.mpiti*.j«ti| tlO.rm.r. 
p. mv.n lnvu.tfa4]PU.S-Tunt..P«r,lt n 
.Tri.n mittl I.Bl,d»pwlUC,lK.<« 
"I .rip.ld and .fctpplnf la .d.**l. 

916 334 2161 



BRBVLOn 

ELECTROniCS 




CIRCLE 102 ON FREE INFORMATION CARD 



fO^ 1 




BRAND NEW! 
FIRST TIME ANYWHERE! 
I B SCIENTIFIC 

INFRARED VIEWER KIT 

* An Easy To Assemble KM 

* Everything You Need Including 
Comprehensive Insiruclton Manual] 

* Li g hi weight Binocular Type Case 
- Faclory Preselected & Prelested 

Components 
■ For Nighl Surveillance. 
E R Communications & Control. 
Document Aulhenticalion, 
Thermal Vsewing. & More 
^•TTjIh Special 
^S yBjT Introductory 

^j^£tr Sruppms & Handling add 

S4 p«r unit i;e out iid*> u.S > 
SPECIFICATIONS: mass hes aod v. sales ?*>: 

Image Converter — lype&Q32 

Special Response — £00 lo 1200 nanomviers iBQD max] 
ResolulLon — 50 l-in*$.fmm 

Magnification — 3X 

Focus Range — 3 It. Eo infinity 

Lens — 1 SOmnv I 30 10* lieid mlrared lelepholo 

and to X Ramsden Eyepiece 
— 90Q nanometer, 4S00 mj* c«ndlepower 

6 V DC (4 J D r " ceJIs or equivj 






$169- 95 



Infrared Sourc e 

C*se 5i*# 

Power Requiremenl - 



Ask tor FREE POLY PAKS CATALOG 



Older by MaU or Call TOLL FREE 

800-343-3086 

W«mi. R*4. Call 017-245-3029 

ORDER SHIPPED IN 24 HRS. 



Poly Pake 

P.O. Box 942, RE-8 
S.Lynnfieid.MA 01940 



CIRCLE 87 ON FREE INFORMATION CARD 



4< 



*KS 



FREE 






CATALOG 

Burglar/Fire Alarms 
Security Products 




Alarm Controls • Remote Stations 
Infrared • Motion Detectors ■ Sirens 

Microwave • CCTV • Fire Detectors 
Vehicle Alarms • Phone Dialers 

Key Locks • Wireless Components 
Magnetic Contacts * Glass Protection 
Lights • System Parts • Tools • Books 

Bells • Ionization Smoke Detectors 



^mountain west 

4215 N. 16th Street Dept. RE-9 
Phoenix, AZ 85016 
1-800-528-6169 



CIRCLE 97 ON FREE INFORMATION CARD 



DON'T 
FORGET 




USE 

YOUR 

READER 

SERVICE 

CARD 




1/0 
SELECTRIC" 
TYPEWRITER 

REDUCED!!! (This Month Only) 
Regularly $399.00 



• Fully Operational 
•TTL Input/Output Laval 

• USE AS A TYPEWRITER 

• Software or Hardware Driven 
•Spare Parts Available, Tod 

• Full 15" Platen 

• IBM Model 745 



These fabulous typewriter-' printers originally 
cost over Si 000.00 each!' Each machine is fully 
tested and operational a nd only require? 5VDG 
and 24 VDC for I/O capability Eleclromc 
Repeat (when activated) Is capable of repeating 
ANY character or key Soon we will be ottering 
software, then hardware interlaces for these 
terrific machines, meanwhile SAVE 50 BUCKS. 



Only $349.00 ea. 

DIGITAL 
MUSICAL KEYBOARDS 

Built to specifications for ARP. 
the world famous Synthesizer Maker 
Features 3 octaves (36 keys) with TTL Decoded: 
6-oa output which determines the note and octave of 
a pressed key Excellent For keyboard inputs lo Micro- 
computer & Digital Synlhesirers and mora. 
NEW UNUSED, keyboard with Electronics 

Write or Call for Our FREE Exciting MEW FLYER"! 




omputer 

roducts & 
.ripherals 
nlimited 



WAREHOUSE 

- i* OHM- 
MAIL ORDERS 
(304 Nrwlan N?w mmppti.ir Q3M$* 



TELEPHONE CmcEHS 

617/372-8637 

Saiif Ho Con-el C«IH 
rd t VISA Aece-pli 



Itcl Cittl r J 

A Acceplpn F^ 



(602) 266-9758 (602) 234-3026 

CXJ ^" SURPLUS *Sf. CXj 
6835 H. 1 6th St. • Phoanix, AZ 8501 6 



MICRO WAVE DOWN 
CONVERTER KIT jhmr ii iyp*| 




PC Bd, 3-MHF9Q1 s. 2-MBD tors, 
1 Thermistor. 1 Ct>oke, 3-Chip Caps. 
^7Q QR * F" Connector. 8 Resistors 
♦ Instruction! 




$19. 90 



BUY BOTH FOB ONLY 



53." 




SPEAKER 
BOX 



w/5" 
SPEAKER 



*1 1 , 95 



PULSE RATE 
INDICATORS 

USED FOR 

HEART MONITORS 

1 00% Functional 



19. 



95 




Includes: 

* 5" LCD Readout 

• ICL 7106 CPL AD 
Decoder Driver 

"MC 14016 
•MC 14013 



' MC 14584 

' LM 32 YN 

■ TL 064 CN 

' Pieio Buteer 

' 9 V Ban. Clip 

1 Misc Eleei Components 



NEW PLASTIC CASE 



$ 



I. 55 



Made for Heart Monitor 
above. 



Includes: 

' 9 V. Ball. Holder 
* Front Beiel 

Excellent lor Frequency 
Counter. 




4" LINE CORD 




450 



CIRCLE 103 ON FREE INFORMATION CARD 



ALL ORDERS SHIPPED SAME DAY VIA UPS 
E-4*"il Pottage & Handling Not Included 
(602)266-9758 (602)234-3026 ™ 

CIRCLE 92 ON FREE INFORMATION CARD 131 



m 

Tl 

H 

m 

CD 

m 

33 

CO 



SPARTAN 



Electronics Inc. 



(516) 499-9500 

6094 Jericho Tpke. 
Commack, N.Y. 11725 



Remote T.V. Converter 

iS^iil 139.95 Ea. 
4 & up 125.00 
60 Channel 
Wireless Control 




Qcommodore Color- 

^=WIG'20^ Sound- 

6 Graphics 

Z] $259. 

Cassette Player $69.00 



Logic Probe 
Global Specialties #LP-2 



S28.49 
DTUTTL/CMOS 




DELUXE 40 CHANNEL 
VHFtoUHF Block 
Converter $38.95 ea. 

Features accessible fine tuning knob 
included: matching X former and two cables 



Surge Stopper Brooks 

4 Outlet w/circuit bkr. 

led/sw $59.79 
1 Outlet 543.50 

Now you can have Maximum Protection / 
(Of your sensitive electronic equipment. v 




Refurbished 

Monitors 12* diagonal 

39.95 



a. 



Atari 800 W/16K ram ses9 

A 

ATARI 



Atari 400 w/ibk $289 



42 Channel CATV 
Converter \ 

■ ■ — - _ 



w/on/off Fine Tuning 
$94.95 



40 Channel VHFtoUHF 

Block Converter 

28.95 Ea. 
24.95 4 & up 




CO 
O 
z 
O 
cc 
F 
o 

LU 



O 

D 
< 

132 



Volume 
Discounts 

Mm Order SIOOQ 
MLT'utir'j slupf , Adfl 
Puces sutfd ra change 
without rrorice 
COD 2.0Q baa 



Visa. MC. BAC. Amen Cnetk. 

COD. Money Oioei 
• Add For Shipping 

» 75 DO « SO 

7600 to 25000 S450 

Z5100H0 50000 1600 

501 00 to 750.00 .$850 

75100 to 1000 00 112.00 

Over 100000 (I? 50 



(516) 

499-9500 



MonTh 
9-8 



TuWF 
9-6 



CIRCLE 86 ON FREE INFORMATION CARD 



BEC BILLET ELECTRONIC* 

P.O. BOX 401244B GARLAND, TX. 75040 (2 14] 278-3553 



Sound Effects Kit $18-50 




ltMBS-4 


nacompJalaaitltial 


■MCiHifi* 


' !'-i;U'ti:i.' DuiUa 


iP/Dflripw 


4bUJ KHjnrf fl'Kll 


*,*■■* ■*!■•■. 


CNmgtwO around 




Tna PtulnrrkHvli 


SN7S4TT 


Sfeirid CMp- UH 


OaaiB pi< 


iKta bwiki .j' UIHI 


EiP vt-'.z^rv ar.rl pati 1a 


COJiIrt 


mt Tirh3vt coll- 


U-naliOm 


ar Sh*54.F O«ill*1or. 


VCO Hoo* Onr S*iol »r 3 


E-..i;c* 


Z&rufpJi *i:,.>2i.i7 


Amp IC r 


v«4 to *npt*m*rH 


an fcOfdi 


■ bl| ' a n r.j[ntrj 


1« -.iii' C^ijrHo' *-rd 


MuWatt* 


OKiiLalof ler r**i 


•nari mMW) fhOV ■ V 


F C Baud Tj',' [j j prototype 



circuitry E«-*y rMagnmnnd 
m c.p-'-tji* EijTloalarti, 

f>ll14r filini. ItaBTl 'r* "[ — 

W*W. i* -HiM* f*u*ftW* *4 
olli*( tOWMtf lha unit tun I 
nultipM ol icai -ci' ic-"i lha 
■aw Put* mClvdH ll> sn>!t 
ta*ernMy manuiJ pjafl*ammnifj cMMl a*itf HJHP>I«3 ftr*TT Ch* 
aptfCilpCAtiens It lufllTJh ji 9V luNary <nd in£lude-3. On boi'S 
T3WW amp w-iii drivi j intiti ipaiftar di'rcily or ih» unit cm br 
co-iTiecIrd la your I'frio wMh inrrf-Qinl r r**ijlrj' 1Sps.1k.4f pqi 
inciudcdi 7MTT li hnckKfed 'tn'iM Mpfcrllrly 1dr J] IS n:.n 



7 Watt Audio Amp Kit $6.95 

SHALL, SINGLE HYBRID IC AND COMPONENTS FIT ON A3" 
x 3" PC BOARD (INCLUDED]. RUNS ON 12VOC. GREAT FOB 
ANY PROJECT THAT NEEDS AN INEXPENSIVE AMP. LESS 

THAN 3»;, THD @ 5 WATTS. COMPATIBLE WITH B6-01 

sound wrr. 



The 

Super Music 

Maker 

REVISION 2 

$2495 

(Bute Kilt 
SEE SPECIAL 
OFFER BELOW 




wtm a prs-prqQrisiwrwt 



On Pot; ti 7 nan *mpl it cr dnvaa. a 
4r d iraetly 



Alnittlactrrj 



C Tnyaic nutr p. 



U+f* arllwr 2704 or 271 ■ EPflOW 

Tor axpandad lunt playing cnpabil- 

no availibl* pra-pr<ig;ra,mm*rj 



don* nucroiWBCCaMP Chip. Tr» Sup*' MtibC Mik»r n crw 



only hi i itu[ dig#i aaiy mWrtien <A pra-pfoqir«inRwJ [una* by p' u W M m °* ta * mamttfy e 

(ROM] c*rB.' K) ijii'dci ROMi with orar 5DD4unaa ir» avMiabte. Uu ihwhn F^tjCw Mom, 
DS*fft*U, D«r AMl«u»ar, rli. IF you htha felt EPflOM ^^runrvir our muiuU wii tom how 
to progrm ydttt gm "un» Kit iikiudwi quuKji, piaiod and dnii«i PC Board and all 
cpmporwrm 

OPTIONAL ACCClfQRIE* 

D1P4W1TCHES 0*i*4c»*,(m* Jpo*. tot luna addfaaa MH/aat 

WALLftuO TRANSFORMER For sparitiwi on i tTVAC Iwuw cunpanl i.ott 

INJECTION MOLDED PLASTIC CASE W/Wffefl! i-dp! A n 

and 2 tivt pa* TfJtkry nvilchu |rtpUc*i DIP i*iecSi«3j 
HrOflMSPEAnEPiwail.a OTunwiih mounlinfl oracJdH . . 



Buy a Sup«i MutiC Makar Kit lot f2* 115 and Qui FREE. ■ ?7DB ROW prn ■ prpgrammBd with J5 
popular tur.Di This oEhr QIvM yOu Ovsr M songa lo chngie Iroml 



Doomsday Alarm Kit $9-95 

41 you nivf \ta j L".e n«apjng and you would 14a lha <tf- at 1ha ratgnlMf hood lo ihara ra-jr 
rmary lhan Utli ■ ■■ i' » Kll will to for youl Tnarc ii no way '<J accuratah/ dMertta um um in My 
huWll, KfCi.Ti jnU term I'Ut Lome Out or :i-ii Htl Four trpatnti' I-:;tc t::i Jla-s ire nued 
cnceiled 1 and ilopprd aE m Marymfl fAl* Id Wi|b) df crpry sattidi A gnj»t lun HI or ■ practical 
aurq-ar iLprrrt Ca-rnplrlfl with PC board and all nflCCIaary COmiwn*ntl !m JDOaKar. For 6- 12 
VDC ODDER DA-rJ? 



THE PRESIDENT SA YS: HOG W A SHE! 

After taking one look it the TRIFUT POWER SUPPLY our engineer declared lhai lha 
units were worth several hurrdred dollars each. He pointed out the engineering, high quality 
cori&l ruction and state-of-the-Art Inlergrated design in support of his position. The President 
or BEC more pragmailoally pointed out the already full warehouse and the two trailer truck 
toads oJ power supplies wailing in Ihe parking lot. and set the price Eo move ihem QUICKLY! 

3 OUTPUTS 
12V t£ IA (12AlnL) 

5V & IDA 
-12V @ SA 
INPUT 10S-12SVAC 



■ UNIT IS COUPLET E LV A?5E HHJiul 
« Fuwd prirrnry tm OC HWIiBni 

- HLMJE 5MI£tDED TnMia.FORUCR 

- ■■-■'■■ i -i 1 I " " i'i;..H' :■» 
i ' -.* i- -p!i- ■.; ■-'■v. 

r ".ntii! Cirrutt F-rolKiiDfi 




62.50 



* 2M Hrvaj* FwCtdtfr 

- Qi#"Bg.pDD mia tf Man. 

- h-jh Eir.« T-icy hrttchtoa "T 

'«4lKM l^t»l!-nt MTWM. 



* 'ntrpi :■■-:;:-"■ 



Piui $5,00 Fnight 

21 Mm. **&-Ax\t *5n*n r EO»H> 

ONE TIME OFFER! LIMIT TWO ill aUJPPUEt PER CUSTOMER, 



COMPLETE UNIT 
lit you TtK«J¥0 n;> 



- COD MIMIMUU Sit DO - ADD S2.M FOR COD 5 

. UPS DELIVtRi AODfleSS MUST ACCOMPANY ALL COD 

ORDERS 
• 11. » HANDLING ON ORDERS UNDER SIH.uO 
. VISA, MC CARD! PR CHECK 
■ ADD 5', FOR SHIP-PtHH] 

I TEXAS RESIDENT! ADD 5* STATE SALES TAK 
' ALL FOREIGN ORDERS ADD £i'> FOR SHIPPING 

'CANADA 1SS| HO POftSW COD'S 
I CALL mn Z7H 3-E-S3I TO PI-ACE CHEDIT CARD OH COD 

tin El* 






Amateur 
32-Element 
Yagi Antenna 



• Not a kit, so it's easier to sell • 1.9-2.5 Ghz 

* 38Vi" long * Die-cast waterproof 
aluminum housing * Withstands temps 
-40° to +140°F. « 50-otim type "N" con- 
nector * Mounting hardware included. 



Only $ 19 



95 



2 Ghz 
MICROWAVE 
ANTENNA 

with 52 dB Overall Gain 

• Built-in down converters * Tune 
1.9-2.5 Ghz • Operates on chan- 
nels 2-6 • 22 dB gain resonant 
disc antenna • Standard 12-16 
vdc power supply • Mounting 
brack lor horizontal or vertical 
polarity • Comes with: 60' coax 
with connectors, 3' jumper cable, 
75-300 ohm and 300-75 ohm 
adapters, complete instruction. 



Q- s 129 



95 



LONG-RANGE MICROWAVE ANTENNAS 

with Separate Down Converters 
FULL-YEAR WARRANTIES! 



I 



:§ 



58 dB 
Gain 



Just 



s 144 



95 



62 dB $^ co 

Gain Only 1 D5J 



95 



• Tuneable temp-compensated L.O. • Power supply with built-in A-8 switch 
■ High gain, low noise ligures ■ Convenient mounting tabs * Weather- 
resistant housings * For distant or low signal areas • Two microwave pre- 
amp stages • 2,1-2.3 Ghz • 20 Mhz input 



■and-width * Noise figure; 5 dB • 

TV channels 2-6 • 75-ohm type "P" output • 50-ohm type "N" input 
mpedance • Aluminum housing • Withstands temps from -40° to -H40"F. 

- —^^^^^Deater inquiries invited. 



INC. 



East Coast: N.C.I 

79-59 264th St. 
Floral Park, N.Y. 11004 
V 212-929-3505/212-544-5990 




West Coast: Galaxy Electronics 

600 N. 61st Ave. 
Glendale, Arizona 85301 
602-247-1151 J 



:s I 



CIRCLE 94 ON FREE INFORMATION CARD 




S^Va1=M. 




G.E. MOV 

Spike Eliminators 

10/*9.90 s 1.29 



Transformer 

Dual bobbin 

30V. 

14V. 1.SAMP 

s 3.00 



y Haunt CRnlari 2'" high 



Chassis (H.D.) 

i ¥& rt '\ Fantaallcl 



115 V. BLOCK FANS 

4V,"SQ. 
#fAN4l 

3" SQ. 
# FAN 31 




s 6.95 



ASSORTED 
LEECRAFT INDICATORS 

#31 

(SNAP-IN) 
RED. AMBER, 
DUALS 
1 15V. 

10/ s 3.95 



.TRANSFORMER 

36V. 

A 200 -M 



99 < 



2Va" Meters 




Any 1 

s 5.95 



Tri-Color LEDS 

s<0? Red Green reverse volt 



^^ Yellow A.C. 



2^1 .50 



^v. Infrared Emitter 
and Photo Diode Detector 
S 2.0Q 



xcsoo-a 

TIL413 



srion leads 



Mura Cordless Telephone 



« 



General Instrument 
Varactor Tuners 

'••1.1 s 22.50 



Mini Switches 

Micro Switch 

■3? 



tr 



SPDT 



ivlong blue paddle fjfy 



Compu-Lite 



red push 

i.i'jmiii.ilo:!:. 



mom #349-1191 



A* In Complete 

with scfi*matjc-s 

s 43.50 




TUSA#DAT25 
IS DB. GAIN 
75 OHM 
SOTOSWMHi 



23.50 



Voltage Regulators 

-<\ 5V. 7805 

-5v. 79M0S 
-6V. 780E5 
- 12V. 781 2 

5/ J 5.50 107*9.95 




MOTOROLA PIEZO SPEAKERS 
fffmf SPECIAL 

rm s 6.95 



3W" 
RESPONSE 
60 TO 30.000 Hi 



C & K Sub Mini ^ 

N.O. Pushbutton /-4^ 

switch io/ s 3.00^/#8631 



Voltage Regulator 
*~^{sK Boards 

XrOL**i~ (v Just hOOk Up 

\r£*! — - to trinsformer 
12V. or9V.1.5A '1.29 



RFI FILTERS 

2 AMP. HOPKINS 

#F.850l0 $-1 



; 1.95 



6 AMP. CORCOM 

#6EF1 



s 2.95 



Dip Tantalum Caps 

6.6. 10 15. 22. 31. 47. to 6 ,3V J0 
22. S8 ft tov. y>^ 

1 5. 33 a 7. 6B (it 16V /nftj, 
15 d 20V. liy G 

SI, 6S, IS. 22 33. J 7 B.B in 35V 
.22. .68. 1 to 50V dippad and send 



KEMET CHIP CAPS 
.018- 100 V. 
MATCH PAIRS 
MIL. SPEC. 

'1.49 



Piezo Elements 
39 



Fantastic 

Mike- Speaker 



■# 



Audio Amplifier 




SEND FOR 
FREE 1982 

Q AT A L OO add l0 *' for sr "PP in 9 ariCl handling min charge $2.50 

orcaii U5al ™;^ s H.J. Knapp of Florida, Inc. 

(813) 392-0406 sine. ■, «. 4750 %th St. N. St. Petersburg, Florida 33708 



CIRCLE 90 ON FREE INFORMATION CARD 




dip sockets' »\^JkPOWER SUPPLIES 



R-lolQ 

■ ox 



UHF 

UNER 



TOP OUALHr. UHF TUNERS ARE 
■ RANO HE*. TESTES, TOP PEP* 
FORMER,! GREAT POP REPLACE' 
WENT USE, CARLE COHVEPTERS, 
KXCRAHRLEP9. KAU *AKl 
L CONVERTERS. ETC ETC 



SOCKET JUMPER 
CONNECTORS 

C-7030 J«*^_C-TOS5 

MPIH 





20 PIN I 

»CCEP1 RIBBCR "•**" *j ?5 

CABLE, CLINCH TO PERM- l-LJ| 
ARERTLT CONNECT DOTH HIVE 
601" COHTACTS 

Brood New 115 VAC 
B Track TAPE DECK 

KITH PLMBACK IMP 




I -I 150 

6 95 



COMPLETE I 

1 TRACK TrUr*! 

3 PORT 

flLTiLiTv 10, LT B'f WOTORCIA with| 

AUTQ TUFlrf DH, EHQ QP 7APL" 5Eh 
SO*, AUTO TRACK CHANQE. IS VAC [ 

iLAPAC.fOr, START MOTOrT. STEREO fl/P 
HEAD AND + IS VDC PL At BACH. E LLC- 
TRQHICT GREAT FOR HOMEBREW 
^HOHE ANSWERERS. RolOT-Sa ET C. 

Stepping MOTORS 

nauA jiftoei. ho 

ClATUriCS A 
IT HP ANGLE 
T.r |.(* MAX 
IPlJEfi OF *DOQ ! 

STEPS/SEC. 401 

ai-iM op Ton- 

CUL. » WATTS 
QrJLjr*,ITiON AB50- 

lij-e error of 0.0*-. 

MOW- CUMULATIVE UflNfl 
•OVB HOOOTI TO LIFE, 
■ UILD P.-T PLOTTER!. HAVE| 

■OilTlONAv FUM' THESE ARt *£w. 
.IJRRENT PROfiUCTlOH. WITH A LIST 
'MICE OVER 4 I QO DO 

i-ZMO (13 LBl 




8hn |6< 

3-OMO 

14 P.. IS* 

S-I+DQ 

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MORE CAIN 

Than a Mitsumi Tuner 

PHILIPS VARACTOR 
TUNER — $23.95 




MODEL ELC 1045 
fREq. RANGE 
LIHF 470-889 MHZ 
CHANNEL 14-B3 

OUTPUT CHANNEL 3 
75 OHM INPUT 



Pirt No. 

D5W10 Philips UHF Tunci ELC 1CHS , . S23.S5 

DSW20 Piinled Circuit Beard. Predrliled 

Class Epoxy $15,00 

D5W30 P.C.B. Poiiiniiomclcrs 5-WK. 1-SK S5.95 

D5VV40 Resistor K.K 1/4 wall 5% 

Carbon Resistors 32 pes 14.95 

DSW50 Panel Mount Porenriometers 

2-10K and Knobs $2.95 

EKW60 IC's 7 pes.. 1 Rcctilier, 

2 Regulators A 1 Heat Sink $15.95 

DSW70 Electrolytic Cap Kil. a pes 44.55 

DSW80 Ceramic Cap Kit 33 pes M.9S 

LESW90 Variable Trimmer Kit. 4 pes 53.95 

DSW100 Coil Kit, 2-10 uh. 1 variable 33 uh 

* 1 - + 37-12 Torold + 26 wire $1.95 

D5W1 10 I C. SoeLels 5-B pins. 2-14 pin $4,95 

D5WT20 Power Transformer 

PRI-117Vac, SEC 24Vac. 1 amp $5.95 

EJSW130 5 peaker. Oval 8 ohm 5J.00 

DSVV140 Misc. Paris, Hardware 4 Hookwire 

Ant. Term, Switch Dpdi, Fuse, 

f useholder. Line Cord, etc $7.95 

When Ordering All Hems 
EMW10-O140 Total Price $99.95 



R.F, Modulator 



Combine both audio and video output onto channel 3 

or 4 ol youf T.V, set. 

Single I.e. chip (MC 1374| makes for quick and easy 

assembly. Single adjustment control! A must for every 

video recording or computer enthusiast. 

VH-0 Kit $19.95 



UHF T.V. Preamp 



Features; 

• 25 dB gain! 

• Kit 



Vour reception will dramatically improve! This unit 
will enable you to pull in signals, you never knew were 
the ret 

For both indoor and outdoor use. Inpul and output 
impedance 75 ohm. No adjustment! Easy assembly. 
|H-0 Kit $22.0,5 



Microwave Receiver 

PS-1 Assembled 32 element antenna $19.95 

PS-2 20 dB gain microwave receiver kit 

with variable power supply kit $50.00 

PS-3 Complete package PS-1 & PS-2 .. ,„ $65.00 
Mounting Hardware Included 



Aviitabfe by Mail Order only 
Send check or money order ro 

STAVIS ELECTRONICS, INC. 

912 W. Touhy Avenue 
Park Ridge, Illinois 60068 
(312) 692-5223 

Minimum order $15.00. Add 10% shipping on ordefs 
under $35.00. Orders over $35.00. add 5*, 
Catalog - $1.00, Visa & Masiercharge acceptable 



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850 I LEC TRONIC TENNIS 

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300 5-30 VOLT RIBULATED PDWEB IUPPL) 

801 IIS iSUNO POATAILE ODOAN 

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Special Prices For Educators 



FREE CATALOG 




• Precision Hand Tools • Test Probes 

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MORE GAIN 

THAN A VARACTOR UHF TUNER 



SATISFACTION 

GUARANTEED 
$15.00 

Frnq. Bangs UHF470- 
86 9MHi Channels 14-83 
Output Channel 3. 
Part No B Available «i request Ch 2 or 4 . 

Modified High Gain Tuner SI 5.00 

1 . The first thing we do is change the standard 
diode tound in every tuner to a Hot Carrier 
Diode. 

2. The tuners output is then measured and 
compared to our computer derived chart 
from which we determine the correct 
value coil to add across the IF output for 
maximum Pre- Peaked gain. 

3. The tuner is fed a standard 1 0db antenna 
input, and while monitoring the output on 
our Spectrum Analyzer, the tuner is tuned 
to the desired channel and its oscillator is 
offset for the desired output frequency as 
follows: 

Ch. 2:58Mhz Cti. 3: 63Mhz Ch. 4: 68Mhz 
We call this step peaking because the tuners output looks like 
a peak on our spectrum analyzer and the highest point ol that 
peak is actually adjusted for the desired output. 

4. Finally, we measure the tuners output one 
more time which is again compared to our 
computer derived performance chart to 
ascertain the correct value of the second 
coll which is added to the tuners internal 
connections. 

This procedure was developed by GILC0 and its our computer 
derived performance charts that make our tuner better. That's 
because almost every tuner gets a different value coil betore 
it's peaked and Ihen a different value coil after it's peaked. The 
combinations are endless and the way we determine the values 
is our secret. 



PRINTED CIRCUIT BOARDS 



Part Mo. B21 Printed Circuit Board SI 7.00 

1. This Printed Circuit Board uses only one 
jumper, others use 9. 

2. The component layout is screen printed on 
the Component side of the pre drilled P/C 
Board, 

3. The solder side of the PK Board is covered 
with High Temperature Solder Resist few- 
ease of assembly. 

4. This P/C board was designed to take advan- 
tage of the Gilco High Gain Tuner which 
means its circuitry is simpler and more 
efficient than those circuits that require 
inferior Varactor Tuners, 



ELECTRON C PARTS KITS 



Part No. B22 Complete Parts Kit S80.00 

All resistors (30). Potentiometers (1-5K, 3-10K), Panel Mount 
Potentiometer (10K), Elecuotyiic Capacitors (6). Ceramic and 
Mylar Disc Capacitors (35). Variable Capacitors (4), All inter- 
allied Circuits ffj. Voltage Regulator, Heat Sink, Diodes (4), IC 
Sockets (4-S pin, 3- 1 4 pin). Power Transformer (24W1A), Coil 
Kit with No. 26 wire (4), Speaker (4"-3 to.), Stanton's, Coaxial 
cable. Ml misc. Hardware, elc. All parts are Individually 
packaged and Labeled. 

All components including the wire. Hardware, Coaxial Cable and 
heat sinks are included in the pans kil. This means your as- 
sembly time from start to finish is only 4 hours. 

Order all 3,620, B21, B22 110.00 

Order 5 each, B20, B21 , B22 95.00/set 



Part No. 

A02 



ACCESSORIES: AMPLIFIERS 



Kit $18.00 



New 2 Stage Low 

Noise 28db gain RF 

Amplifier Specially 

designed for kit builders 

Newl StageLow Kit S10.SO 

Noise 14db gain 

Amplifier 

75-300 OHM matching 

Transformer. 

Coaxial Connectors. . . 

Mill order only. Sand check or money order to: 

GILCO INTERNATIONAL, INC. 

P. 0. Box tin, Ceraf Gibkrt, FL 33124 

Tel. (305) 823 5891 For COD orders add 10% shooing 

and handling or for orders over 550. add 5%. 

PL reiMtttti add 5% met tax. Please wrtta tor more Mvnuden 



A03 



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Full-Spec Microwave Devices PC Board Kit and Supplies 



Pkg. of 2 




Two4*/2x3" boards, 
reslst-ink pen, solvent, 
etcham, layoji strips and 
circles, lank, Vie" drill bit, 
instruct ions, 

276-1576 8.95 

Extra flesist-Ink Pen. 

276-1530 1.3B 

Extra Elchant. 16 oz. 
276-1535 2,49 



05062-2835. Low-noise Schottky barrier 
diodes. Ideal for UHF and microwave stripline 
mixers. Maximum capacitance: 1 pF. 

276-1124 Pkg, of 2/1.99 

SEMRF-901. Low-noise NPN transistor for use 
to beyond 2000 MHz. Beamlead-style macro-X 
case. 300 mW. 276-2044 2.99 

Computer Connectors 




Direct-Etch Dry Transfers 

Easy to Use! 
Set of 4 



» 



Low As 



-|49 




259 



Transparent sheets with rub- 
on circles, strips, component 
pads and more. Press on to 
a copper clad PC board and 
you're ready to etch— with 
pro-b,uatily results 
276-1577 Set/2. 59 



• High Accuracy 

• Great for FSK, Modems 

9400. This bipolar/CMOS device accepts an 
analog voltage and generates a proportional 
frequency, or provides an output voltage in pro- 
portion to input frequency. Operates up to 1 00 
kHz. See our Engineer's Notebook II for circuit 
ideas. Single/split supply. 276-1790 3.49 



Miniature DPDT Relay With 
12VDC Coil 



Adjustable PC Board Holder 



EJ 4-Pin DIN-Type Plug. For audio and micro- 
computer use. 274-007 1,49 

(B 40-Position Card Edge Connector. Highest 
quality, reusable. For ribbon cable. 

276-1558 4,95 

OS-Pin Inline Jack, Accepts 3 or 5-pin plugs. 
Solder terminals. Strain relief. Shielded. 
274-006 1.49 




695 



Frees hands for easier sol- 
dering and repair. Mounts on 
bench or In a vice. Holds 
board securely, yel is fully 
adjustable. 276-1568 6.95 




Socket 
Included 



469 



Top quality! Long-life 
contacts rated 3 amps at 
125VAC. Coil: 75 milli- 
amps, 160 ohms. Relay, 
1 'A x 1 x %". Includes 
Chassis or PC-mount 
socket with clip for relay. 
275-206 4.69 



Panel Lettering 



259 



4 sheets with rub-on 
letters, symbols, 
numbers and more. 
270-201 2.59 




SPDT Lever Switch 



-|49 

Submini, W 
roller lever. 
5 amps at 
250VAC. 
275-017.. .1.49 





Mike Element 
299 



Omnidirectional 
Electret. 3/8" 
dia. 4-10VDC. 
270-092 . . 2.99 



Motorola-Type Jack 

990 




With 4'fc-inch shielded 
cable. For scanners, car 
radio hookups. 
274-713 99C 



DC Buzzer 




Cut 42% 

690 



Reg. 
1,19 



Super loud! 1.5- 

3VDC with low 

current. 

273-004 . Sale 69C 



"Battery" Clips 




Set. of 2 
One Red 
Dm W»c* 



Versatile Solenoid 




Ideal lor robots, 
model rail- 
roads, opening 
valves, door 
latches and 
more. Spring 
return plunger. 
31 ohms, 430 
milliamps at 
12VDC. 
273-251 . . 3.99 

1%x.lVnx1V»* 



Fit car battery posts. 
Crimp or solder. 
270-344 . . Set t.19 



Low-Cost Light Dps! 



Dress Up and Protect Your Project! 

S3 IB 




Panel Meter Sale! 




10 95 





S) Deluxe Two-Tone Enclosure. ABS plastic end panels for easy drilling, 
interna! slots and standoffs for PC boards, self-stick feel. 2'A x 5 x 5'/«". 

270-218 7.95 

"Stlver-Look. " Both feature vented steel tops, easy-to-work aluminum 
chassis, rubber feel and very classy "silver' finish. 

(l)3V.x7*x5'A". 270-229 . . 9.95 [C!2V.x5V..xW. 270-226 6.95 
E) "Handle" Box. Easy to carry Vented steel top with black finish, alumi- 
num front and boltom, rubber feet. 5V>x9'fex6V.\ 270-270 10.95 



I- R88 



Each 



Micronta* precision at 23% off! 
Jeweled movements. Large, easy- 
to-read faces, 
to 50 Microamps DC. 

270-1751 Sale 6.88 

to 1 Milliamps DC. 

270-1752 Sale 6.88 

to 15 Volts DC. 

270-1754 Sale 6.88 



A Micro 12V Lamps. One red, 
one green 60 mA. Metal panel rec- 
ommended. 

272-334 Pkg. of 2/1.69 

[B Push-In Neon Panel Lamps. 
One red, one green. BuilHn drop- 
ping resistors tor 120V use. 
272-709 . - Pkg. of 2/1.99 

IS Yellow LEDs In Chromed 
Holders. 276-073 Pkg. ot 2/1.69 
LP) Orange Rectangular LEDs. 
Hi brightness 
276-074 Pkg, of 2/99C 



Radio /hack 



A DIVISION OF TANDY CORPORATION • OVER 8400 LOCATIONS IN 80 COUNTRIES 

Retail prices may vary at individual stores and dealers 
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5101 

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2147 

TMS4044-4 

TMS4044-3 

TMS4044-2 

MK4118 

TMM2016 

HM8116-4 

HM6116-3 

HM6116-2 

HM6116LP-4 

HM6118LP-3 

HM6116LP-2 

2-6132 



266x4 
256x4 
1024 x 1 
1024 x 1 
1024 x 1 
256x4 
256x4 
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1024 X 4 
1024 X 4 
4096x1 
4096x1 
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4096x1 
1024 x 8 
2048 x 8 
2048 x 8 
2048 x 6 
2048x8 
2048 X a 
2048 x 8 
2048 x 8 
4096x8 



(450 ns) 

(cmos) (450ns) 

(450ns) 

(LP) (250ns) 

(LP) (450 ns) 

(450ns) 

(450 ns) 

(450ns) 

(LP) (200ns) 

(LP) (300ns) 

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(55ns) 

(450ns) 

(300ns) 

(200ns) 

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(150ns) 

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(Qstal) (300ns) 34.95 
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.85 
1.55 
1.15 
2.49 
2.79 
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2.10 
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3.25 
3.75 
4.25 
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TMS4027 

MK4108 

MM5298 

4116-120 

4116-150 

4116-200 

4118-250 

4116-300 

2118 

MK4816 

4164-200 

4164-150 



4096X 1 

8192 x 1 

8192 x 1 

16384 k1 

16384 x 1 

16384x1 

16384x1 

16384x1 

16384 x 1 

2048x6 

65536x1 

65536 x 1 



(5v) 
<Sv) 
(5v) 
(Sv) 



(250 ns) 
(2O0ns) 
(250ns) 
(120ns) 
(150ns) 
(200ns) 
(250ns) 
(300ns) 
(150ns) 
(300ns) 
(200ns) 
(150ns) 



Each 

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100 

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EPROMS 



1702 
2708 
2758 
I TMS2516 

2716 
1 27161 
I TMS2716 
' TMS2532 

2732 

2732A-2 

2764 

TMS2564 



256x8 
1024 x 8 
1024 X 8 
2048 x 8 
2048 X a 
2048 x 8 
2048 X a 
4096x8 
4096x8 
4096x8 
8192 x 8 
8192 x 8 



(Ills) 
(450ns) 
(5«) (450n3) 
(5v) (450ns) 
(5v) (450ns) 
(5v) (350ns) 
(450ns) 
(5v) (450 ns) 
(5v> (450ns) 
(5v) (200ns) 
(5«) (450ns) 
(5v) (450ns) 



8 

Each pes 

4.95 4.50 

3.75 3.50 

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6.95 5.85 

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9.00 8.50 

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83.00 


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5,200 


119.00 


PE-24T 


X 


9 


6,700 


175.00 


PL-265T 


X 


20 


6,700 


255.00 


PB-125T 


X 


16 


15,000 


349.00 


PR-320T 


X 


32 


15,000 


595.00 



Z-80 




2.5 Mhi 


Z80CPU 


6.00 


Z80-CTC 


5.95 


ZBO-DART 


15.25 


Z80-DMA 


17.50 


Z80-PIO 


6.00 


zeo-siora 


18.50 


ZBO-SIO/1 


18.50 


Z80-SIO(2 


18.50 


Z80-SIO/9 


16.95 


4.0 Mhz 


zboa-cpu 


8.00 


Z80A-CTC 


8.65 


Z80A-DART 


18.75 


Z80A-DMA 


27.50 


Z80A-PIO 


6,00 


Z80A-SIO/0 


22.50 


Z80A-SIO/1 


22,50 


Z80A-SIO/2 


22.50 


Z80A-SIO/9 


19.95 


6.0 Mha 




zbob-cpu 


17.95 


Z80B-CTC 


15.50 


Z80B-P1O 


15.50 



8200 



ZILOG 

Z6132 34.95 

ZS671 39.95 



34.95 
3.50 
1.85 
3.85 
1.80 
2.50 
1.80 
4.90 

19.95' 
4.95 
4,45 

14.95 
4,75 
9.25 
9.85 
4.75 
5.25 
8.50 
8.95 
6.90 
7.50 

39.95 

29.95 
9.50 

10.00 
8.65 
6.65 
5.70 
6.65 
6.50 

25.00 

49.95 



ORDER TOLL FREE 

800-538-5000 
800-662-6279 

(CALIFORNIA RESIDENTS) 

IF YOU CAN FIND A PRICE LOWER 
ELSEWHERE, LET US KNOW AND 
WE WILL BEAT THEIR PRICE. 

* Computer managed inventory — 
virtually no back orders. 

* Guaranteed lowest prices! 

* Fast service — most orders 
shipped within 24 hours! 



MONTHLY SPECIALS 

CPU SALE 

8 BIT 

I Z-80 cpu 2mhz '3.95 (10/ 3.75 ea) 

6502 1 mhz *5.95 (10/ 5.7s ea) 

1 6809 int. clock s 12.95 (10/11.25 ea> 

16 BIT 

8086 s 29.95 

68000 8mhz s 99.95 

SALE ENDS SEPT. 30. I9BZ PLEASE STATE 
SEPTEMBER SPECIALS" WHEN ORDERING 



8000 

8035 
8039 
INS-8060 
INS-8073 

soao 

8085 
8085A-2 



8155 
8156 
8185 
8185-2 

8741 
8748 
8755 



7.25 

7.95 

17.95 

29.95 

3.95 

7.95 

11.95 

59.95 

39.95 

89.95 

7.95 

8.95 

29.95 

39,95 

39.95 

29.95 

32.00 



DISC CONTROLLERS' 



1771 

1791 

1793 

1795 

1797 

6843 

8272 

UPD765 

1691 

2143 

INTEHFACE 

8T26 

8T28 

8T95 

8T96 

8T97 

BT98 

DM8131 

DPB304 



21.95 
29.95 
38.95 
54.95 
54.95 
34.95 
39.95 
39.95 
18.95 
1895 

1.69 

2.49 

.99 

.99 

.99 

.99 

2.95 

2.29 



MISC 



3341 

76477 

AY3-8910 

MC3340 

95H90 

11C90 

8202 A 

3242 

MC3480 

MC4024 

MC4044 

3205 

BIT-RATE 
GENERATORS 



4.95 

3.95 

12.95 

1.49 

7.99 

13.95 

34.95 

7.95 

9.00 

3.95 

4.50 

3.50 



14411 
BR1941 
4702 

COM5016 
MM 5307 

UARTS 

AY3-1014 

AY5-1013 

PT1472 

TB1502 

2350 

TMS6011 

I M 8402 

I M 6403 

INS8250 



11.95 
11.95 
12.95 
16.95 
10.95 

6.95 
395 
9.95 
3.95 
9.95 
5.95 
7.95 
8.95 
14.95 



KEYBOARD CHIPS 



AY5-2376 
AY5-3600 
74C922 
74C923 
CLOCK 
MM5314 
MM5369 
MM 5375 
MM58167 
MM58174 
MSM5832 



11.95 
11.95 
5.25 
5.50 
CIRCUITS 
4.95 



68000 

6800 

6802 

6808 

6809E 

6809 

6810 

6820 

6821 

6828 

6840 

6843 

6844 

6845 

6847 

6850 

6852 

6860 

6862 

6875 

6880 

6883 

68047 

88488 



6800 



call 

4.95 

10,95 

13.90 

19.95 

19.95 

2.95 

4.95 

4.95 

14,95 

12.95 

34.95 

25.95 

16.95 

12.25 

3.45 

5.75 

10.95 

11.95 

6.95 

2.95 

24.95 

24.95 

19,95 



6800 = 1MHZ 



6SB00 
68B02 
68B09E 

68B09 
68810 
68B21 
6BB45 
68B50 
68 BOO 



10.96 
22.25 
29.95 
29.95 
7.95 
12.95 
35.95 
12.95 
2 MHZ 



s500 



6502 
6504 
6505 
6507 
6520 
6522 
6532 
6545 
6551 



2 MHZ 



6502A 
6522A 
6532A 
6545A 
6651 A 



6.95 
6.95 

8,95 
9.95 
4.35 
8.75 
11.25 
22.50 
11.85 

9.95 
11.70 
12.40 
28.50 
12.95 



CRYSTALS 



32.768 Khz 

1.0 mliz 

1.8432 

2.0 

2.097152 

2.4576 

3.2788 

3.579535 

4.0 

5.0 

5.0888 

5.185 

5.7143 

6.0 

6.144 

6.5536 

8.0 
10.0 

14.31818 
15.0 
16.0 
18.0 
18.432 
20.0 
22.1184 
,32.0 



1.95 
4.95 
4.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3.95 
3. 95 j 



M-F.S:n- 3 JDR MICRODEVICES, INC. 

VISIT OUR 1224 S. B'ascom Avenue 

RETAILSTORE San Jose, CA 95128 

800-538-5000 • 800-662-6279 (CA) 
(408) 995-5430 • Telex 1 71 -1 1 



ViSA 



PLEASE USE YOUR CUSTOMER NUMBER WHEN ORDERING 
TERMS. For shipping include 52 tor UPS Ground or S3 lor UPS Blue 
Label Air. items over 5 pounds require additional shipping charges. 
Foreign orders, include sufficient amount tor shipping. There is a St 
minimum order. Bay Area and Los Angeles Counties add 6 1 s 1 .- Sales 
Tax. Other California residents add 6 Sales Tax. w- reserve the 
right to substitute; manufacturer. Not responsible tor typographical 
errors. Prices are subject to change without notice. We will match or 
benl any competitor's price, provided it is not below our cos I. 



CIRCLE 71 ON FREE INFORMATION CARD 



2716 



16K EPROMS 



8/ $ 3 



ALL MERCHANDISE 100% GUARANTEED! 



2732 



32K EPROMS 



8/ $ 7 



95 

EACH 



CALL US FOR VOLUME QUOTES 



74LS00 



IC SOCKETS 



74LSO0 


.25 


74LSS5 


1.15 


74LS168 


1.75 


74LS295 


1.05 


1 LM301V 


.34 


LM1800 


299 


74LS01 


,25 


74LS86 


.40 


74LS169 


1.75 


74LS298 


1.20 


1 LM308V 


.98 


LM1889 


2.49 


74LS02 


.25 


74LS90 


.65 


74 LSI 70 


1.75 


74LS324 


1.75 


1 LM209K 


1.49 


LM3900 


.59 


74LS03 


.25 


74LS91 


.69 


74LS173 


.80 


74LS352 


1.55 


1 LM311 


.64 


LM 3909V 


.98 


74LS04 


.25 


74LS92 


.70 


74LS174 


.95 


74LS353 


1,55 


1 LM317T 


1.95 


LM3914 


3.95 


74LS05 


.25 


74LS93 


.65 


74LS175 


.95 


74LS383 


1.35 


1 LM317K 


3.95 


LM3915 


3.S5 


74LS08 


.35 


74LS95 


.85 


74LS181 


2.15 


74LS364 


1,95 


I LM318 


1.49 


LM3916 


3.95 


74LS09 


.35 


74LS96 


.95 


74 LSI 89 


9.95 


74LS365 


.95 


I LM323K 


4.95 


75451V 


.39 


74LS10 


.25 


74LS107 


.40 


74LS190 


1.00 


74LS386 


.95 


1 LM324 


.59 


75452V 


.39 


74LS11 


.35 


74LS109 


.40 


74LS191 


1,00 


74LS367 


.70 


I LM337K 


3.95 


75453V 


.39 


74LS12 


.35 


74LS112 


.45 


74LS192 


.85 


74LS368 


.70 


I LM339 


.99 






74LS13 


.45 


74LS113 


.45 


74LS193 


.95 


74LS373 


1.75 


I LM377 


2.29 


Bl FEt 


74LS14 


1.00 


74LS114 


.50 


74LS194 


1.00 


74LS374 


1.75 


1 LM380 


1.29 


TL071 


.79 


74LS15 


.35 


74LS122 


.45 


74LS195 


.95 


74LS377 


1.45 


■ LM3SSV 


1.50 


TL072 


1.19 


74LS20 


.25 


74LS123 


.95 


74LS196 


.85 


74LS378 


1.18 


■ LM555V 


.39 


TL074 


2.19 


74LS21 


.35 


74LS124 


2.99 


74LS197 


.85 


74LS379 


1.35 


I LM556 


.69 


TL081 


.79 


74LS22 


.25 


74LS125 


.95 


74LS221 


1.20 


74LS385 


1.90 


I LM565 


.99 


TL082 


1.19 


74LS26 


.35 


74 LSI 26 


.85 


74LS240 


1.29 


74LS386 


.65 


■ LM566V 


1.49 


TLOB3 


1.19 


74LS27 


.35 


74LS132 


.75 


74LS241 


1.29 


74LS390 


1.90 


I LM567V 


1.29 


TL084 


2.19 


74LS28 


.35 


74LS136 


.55 


74LS242 


1.85 


74LS393 


1.90 


■ LM723 


.49 


LF347 


2.19 


74LS30 


.25 


74LS137 


.99 


74LS243 


1.85 


74LS395 


1.65 


I LM733 


.98 


LF351 


.60 


74LS32 


.35 


74LS138 


.75 


74LS244 


1.29 


74LS399 


1.70 


■ LM741V 


.29 


LF353 


1.00 


74LS33 


.55 


74LS139 


.75 


74LS245 


1.90 


74LS424 


2.95 


I LM747 


.79 


LF355 


1.10 


74LS37 


-55 


74LS145 


1,20 


74LS247 


.75 


74LS447 


.37 


■ LM74BV 


.59 


LF356 


1.10 


74L.S38 


.35 


74LSU7 


2.49 


74LS248 


1.25 


74LS490 


1.95 


I LM1310 


2.90 


LF357 


1.40 


74LS40 


.35 


74LS148 


1,35 


74LS249 


.99 


74LS624 


3.99 


■ MC1330V 


1.69 






74LS42 


.55 


74LS151 


.75 


74LS251 


1.30 


74LS668 


1.69 


■ MC1350V 


1.29 


EXAR 


74LS47 


.75 


74LS153 


.75 


74LS253 


.85 


74LS669 


1.69 


■ MC1358 


1.79 


XR2206 


3.75 


74LS48 


,75 


74LS154 


2.35 


74LS257 


.85 


74LS670 


2.20 


■ LM1414 


1.59 


XR 2207 


3.85 


74LS49 


.75 


74 LSI 55 


1.15 


74LS258 


.85 


74LS674 


9.65 


■ LM 1458V 


.69 


XR2208 


3.90 


74LS51 


.25 


74LS158 


.95 


74LS259 


2.85 


74LS682 


3.20 


■ LM1483 


.99 


XR2211 


5.25 


74LS54 


.35 
.35 

1.25 
.40 


74LS157 
74LS158 
74LS160 
74LS161 


.75 
.75 
.90 
.95 


74LS260 
74LS266 
74LS273 
74LS275 


.65 

.55 

1.65 

3.35 


74LS683 
74LS684 
74LS685 
74LS688 


2.30 
2.40 
2.40 
2.40 


K.LM1489 


.99 


XFL 2240 


3.25,, 


74LS55 
74LS63 
74LS73 












VOLTAGE 




74LS74 


.45 


74LS162 


.95 


74LS279 


.55 


74LS689 


2 40 


REG 




74LS75 


.50 


74LS183 


.95 


74LS280 


1.S8 


74LS783 


24.95 


1 7305T 
1 7808T 
1 781 2T 
1 7815T 
1 7824T 


.69 
.89 
.69 
.89 
.89 

1.39 


7905T 
7908T 
791 2T 
791 5T 
7924T 

7905K 


.99 
.99 
.99 
.99 
.99 


74LS76 


.40 


74LS164 


.95 


74LS283 


1.00 


81LS95 


169 


74LS78 


.50 


74LS165 


.95 


74LS290 


1.25 


81LS98 


169 


74LS33 


.75 


74LS166 


2.40 


74LS293 


1.85 


81LS97 

81LS98 


189 
1.69J 


















1 7805K 


1.4S 


















1 7812K 


1,39 


7912K 


1.49 








WE HA 








1 781 5K 


1.39 


7915K 


1.49 


* 74C00 


* 74S00 


• TRANSISTORS 




1 7824 K 


1.39 


7924K 


1.49 


* 7400 


* LINEAR 


* . 


. . and much more! 


1 78 LOS 
■ 73L12 


.89 
.69 


79L05 
79L12 


.79 
.79 


















1 78L15 


.89 


7SL15 


.79 


















T = 


TO-220 
L = 


K = TO 
TO-92 


3 























I ANTHANA SS SO SOFT 24,951 

I WABASH SS SD SOFT 24.9sl 

I VERBATIM SS SD SOFT 23.951 

| VERBATIM 10 SECTOR HARD 29.9$| 

8" 

^VERBATIM SS SD SOFT .. 

MONITORS" 

\ ZENITH ZVM-1 21 \ 

$119.95 

NEC JB-1201M 

$169.00 



FAN 

$69.00 



* Outlet on rear. 

* Simply snap over 
air vents. 

* Quiet motor. 



EPSON 
PRINTERSI 

MX- 80 

MX- 80FT 
MX-100 
CALL FOR PRICE 



8 pin ST ,13 


,11 


14 pin ST .15 


.12 


16 pin ST ,17 


,13 


18 pin ST .20 


.18 


20 pin ST .29 


.27 


22 pin ST .30 


.27 


24 pin ST .30 


.27 


28 pin ST .40 


.32 


40 pin ST .49 


.39 


ST « SOLOERTAIL 


8 pin WW .59 


.49 


14 pin WW .69 


.52 


16 pin WW .69 


58 


18 pin WW .99 


.90 


20 pin WW 1.0a 


.98 


22 pin WW 1.39 


1.28 


24 pin WW 1.49 


1,35 


28 pin WW 1.69 


1.49 


40 pin WW 1.99 


1.80 


WW = WIRE WRAP 


CONNECTORS 


RS232 MALE 


3.25 


RS232 FEMALE 


3.75 


RS232 HOOD 


1.25 


S-10O ST 


3.95 


S-100WW 


4.95 



DIP 
SWITCHES 

i POSITION .85 I 

5 POSITION .90 

6 POSITION .90 

7 POSITION .95 

8 POSITION .96 



LED LAMPS 

100- | 
1-99 up 

Jumbo 

Red .10 .09 I 

Jumfao 

Green .18 .15 | 
Jumbo 

Yellow .18 .151 



4011 
4012 
4013 
4014 
4015 
4016 



4071 
4072 
4073 
4075 
4076 
4078 
4081 
4082 
4085 
4086 
4093 
4098 
4099 



,30 
.30 
.30 
.30 
.95 
,30 
.30 
.30 
.95 
.95 
.95 
2.49 
1,95 



4017 1.15 

4018 .95 

4019 .45 

4020 .95 

4021 .95 

4022 1.15 

4023 .35 

4024 .75 

4025 .36 

4026 1.65 

4027 .65 

4028 .80 

4029 .95 

4030 .45 

4034 2.95 

4035 .85 

4040 .95 

4041 1.25 

4042 .75 



14409 12.95 

14410 12.95 

14411 11,95 

14412 12.95 
14419 4.95 
4502 



4503 
4508 

4510 
4511 
4512 
4514 
4515 
4516 
4518 
4519 
4520 
4522 
4526 
4527 
4528 
4531 
4532 
4536 
4539 
4543 
4655 
4556 
4581 
4582 
4584 
45B4 



.95 
,65 

1.95 

.95 

.95 

.95 

1.25 

2.25 

1.55 

1.25 

1.25 

1.25 

1,25 

1.25 

1.95 | 

1.25 

.95 

1.95 

1.95 

1.95 

2.70 

.95 

.95 

1.95 

1.95 

.95 

.95 



CALL US FOR 

YOUR 74COO 

REQUIREMENTS 



ADDON 

DISK 
DRIVE 

FOR Apple* II 

* Includes metal cabinet 

* Color matches Apple* 

* 35 Tracks/single side 

* Includes cable 

* Use with Apple* II 
Controller 

$37500 

'Apple is a trademark of 
APPLE COMPUTER INC. 



16K APPLE* 
RAM CARD 

Upgrade your 48K Apple* II to full | 
64K of RAM. 

Fully software and hardware com- 
patible with the Apple language j 
card and microsoft Z80 card. 
Eliminates the need for the Apple- 1 
soft or Integer Basic ROM card 
when used in conjunction with 
DOS 3.3. 

Allows you to run Apple Fortran 
or Pascal with no difficulty. 
Available as bare board, kit, or | 
assembled and bested board. 

I BARE BOARD $40.00 

KIT 69.96 

[ASSEMBLED & TESTED . . . 74.95 

"Apple it 3 trademark ot APPLE COMPUTER INC. J 



M-F. 9° u sl 1 3 JDR MICRODEVICES, INC. 

VISIT OUR 1224 S. Bascom Avenue 

RETAILSTORE San Jose, CA 95128 

800-538-5000 • 800-662-6279 (CA) 
{408) 995-5430 • Telex 171-110 



PLEASE USe YOUR CUSTOMER NUMBER WHEN ORDERING 
TERMS: For shipping include S? lor UPS Ground or S3 lor UPS Blue 
Label Air. Item; over & pounds require additional shipping charges. 
Foreign orders, include sullicienlamo:*nl lor ^hipping There isaSIQ 
minimum Ofder. Bay Area and Los Angeles Counties add fi' , i Salts 
Td*. Other California residents add 6 Sales Ta«, We reserve (he 
right lo substitute manufacluref. Nol responsible tor typographical 
errors, Prices are subject to cnange withoui notice. We will match or 
b-eal any competitor's pnce provided it ii nol below our cosl b 



CIRCLE 71 ON FREE INFORMATION CARD 



g 

z 
o 

IX 

r- 
o 

LU 



Q 
a 
< 

EC 



CABLE TV 
CONVERTERS 

AND OTHER 
GOOD STUFF! 



SMASHING ALL SALES RECORDS - OUR NEW 
M CH ANNE L CABLE TV CONVERTS R< 




QUARTER-MILE WIFELESS MICROPHONE 
a RECEIVER SYSTEM 




i95 



*CC *i-,irow.l ft-yHll f or ! "Oi r-3 

AKtt&irnim Ml 
fcur'pi v 4Hrilnl f ;htI ■« I m«S9 
«*.« ran* 
■»*■ Ha 




FACTORY SURPLUS VHF / UHF 
TWIN 'VARACTOR TUNERS' 



rV 'f HDNT ENftS" Aturdii 
No. Itavcwt 



2Q95 



DUMPING! NOHELCO ENDLESS LOOP CASSETTES' 

4Q C ImpeMib r Ed fra jr «nv 

7 ? p««i 
3 fPiinutii - hie, 34BVA«» J2^*Zhs.\ T 




rN STOCK- THE MURA 
CORDLESS TELEPHONE SYSTEM! 







*i<* 3JGVA374 



14C 



9 



SALE OF QUARTZ BATTERY 
OPERATED CLOCK MOVEMENTS' 

ftf AtfUFte* flf ' J"'" tlir up 

MM 5*rrunr N» VIVAM1 



20 AMP REGULATED 12VDC POWER SUPPLY! 



U(**ISni>lojrJ. |35rfC Hulk 

Ippd (<v ly hamdiri ham sinion- 
mnri* r+uuj. SSB I in**'! up Id 

■4IKM fif 9r|hd rrlw fiClQfV 

iuWi 1 ID VAC ft« M$VA3M 



3J HVA3JJ Ti .bo.< I D imp* -EM.BS *4ft« mUSI 



#oe 



BE3BIE3 



OUR LATEST 9B PAGE 
FASCINATING CATALOG 
-1«m n*:*rd **"A Lr"-n«p 




i Wnii t> t<r< irwunfaf 



ETCO ELECTRONICS 

NORTH COUNTRY SHOPPING CENTER 

PLATTSflURGH. N.Y. 12Wt 



(UN 1 518-561 8700 



ADVERTISING INDEX 



RADIO-ELECTRONICS does not assume 
any responsibility for errors that may 
appear In the Index below. 



Free Information Number 



Page 



SO AMC Sales 91 

26 AP Products, Inc 30 

Aaron Gavin 76 

65 Abex 104 

74 Active Electronics 119 

77 Ad vance Computer Prod ucts 117 

— Advance Electronics 2S- 29,3 2 . 77 

79 All Electronics 127 

22 William B. Allen Supply Ill 

52 Anders Precision 

Instruments Co., Inc 110 

20 Antenna Specialists 79 

92 Arizona Electronics 131 

89 B.G. Micro 130 

40 B&K Precision Dynascan Corp, 94 

102 Babylon Electronics 130 

34 Barker & Williamson 90 

— Karel Barta 114 

10 Bishop Graphics, Inc 31 

— Bullet Electronics 132 

— C & D Electronics, Inc 130 

— CIE, Cleveland Institute of 

Electronics 18-21 

67 CRT 105 

24 Cambridge Learning 103 

101 Chancy Electronics 120 

— Command Productions 118.138 

16 Communications Electronics 2 

Components Express 106 

103 Computer Products & 

Peripherals Unlimited 131 

81 Concord Electronics 120 

— Contact East 134 

— Cook's Institute 118 

— Dage Scientific 118 

— Data Services Co 118 

— Devt ronix/Organ Products 114 

91 Diamondback 133 

Dlgatek Corp. 114 

100 Digicom Engineering, Inc 114 

73 Digi-Kcy Corp 123 

80 Dokay 116 

31 Edsvn 112 

19,— Elec'tra Company 25,114 

25 Electronic Rainbow, Inc 95 

— Electronic Specialists, Inc, 108 

— 88 Etco Electronics 118,138 

57 Etronix 110 

58 Firestone Tarp. Mfg 110 

IS Fluke Mfg, Co., Inc. 5 

— Fordham Radio 118 

70 Formula Internationa] 128-129 

— Gileo International, Inc 134 

53,54 Gladstone Electronics 94 

11 Global Specialties Corp 81 

— Global TV Electronics 114 

82 Godbout Electronics 122 

— Grantham College of Engineering.. 109 

— Grove Enterprises, Inc. ...... .... 116 

23 Hal Communications Corp 34 

99 Hal-Tronix 127 

—,—,2 Heath Cover 111,15,87-89 

35,36,37 Hlckok Electrical 1 nst rum entsSS ,90 , 1 08 

14 Hitachi Denshi America, Ltd 44 

95 Hltech Electronics 126 

98 Information Unlimited 127 

49 International Crystal .....107 

71 JDR, Microdevices 136-137 

— J&W Electronics ..,.,,...,,, 116 

69 Jameco Electronics 124-125 

56 Jan Crystal 109 

90 HJ. Knapp 133 

4,5 Leader Instruments Corp Cover II 

— McGee's Radio 118 

McGraw-Hill Book Co 36-39 

— McKay Co 1 14 

76 MCM Audio 1 15 

63 Masco Electronics 104 

42 Micro Management Systems, Inc. .. 1 13 

— Microtenna Associates 116 

— Monarchy Engineering, Inc, 130 

97 Mountain West/Alarm 131 

9 Multilech Electronics, Inc 27 

NRI Schools 8-11 

NTS Schools 96-99 

— Nabih's, Inc 110 



94 Neptune Communications, Inc, 132 

— Netronics 75,82 

32 North American Soar 82 

17 O.K. Machine & Tool 13 

28 Omnitron Electronics 102 

84 P.P.G. Electronics Co., Inc 134 

43 Pac-TecCorp 107 

55 Paia Electronics 107 

7 Panasonic ] 

39 Panavise... 76 

Philips ECG 33 

13 Philips Test & Measuring 

Instruments 41 

41 Plait Luggage 112 

87 Poly Paks 131 

38 Protecto Enterprises 76 

RCA 26 

75 Radio Shack 135 

72 Ramsey Electronics 121 

96 SCR Electronics, Inc 126 

62 SMP, Inc 104 

66 SRS 105 

— Sabadia Exports Corp 120 

33 H.W. Sams 93 

— Satellite TV 114 

104 Shure Brothers 109 

— Simple Simon Electronics... 85 

21 Simpson Electronics Co 24 

— Sinclair Research, Ltd 16-17 

27 Sintec Co 91 

78 Solid State Sates 126 

86 Spartan Electronics 132 

59,— Spectrum Electronics 104.1 16 

93 Stavis Electronics, Inc 133 

— Suntronics Co., Inc. 120 

61 Symmetric Sound Systems 105 

IS TAB Books 83 

— Tektronix 7,22-23 

46,47 Triplet! Corp 100 

41.45 Triton Marketing Corp 113 

6,63 Ungar-Dtvision of 

Eidon Industries 35,105 

64 Universal Enterprises 105 

29 Vaco 101 

48 Vector Electronics Co 107 

60 Video Control 105 

8 VIZ Mfg. Co 43 

51 Wersi Electronics ... 91 

— Zenith Radio Co Cover IV 



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Let's get personal 



try out the in-stock selection of Heath/ 
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Mnim awailahlo at wmir noarhw Hpathkit 



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New from Zenith! 



Ttoo-wa y protection from high 
voltage surges lor the appliances 
and electronics you sell or service! 



A brief, high voltage surge - or 
spike - can occur in any electrical 
system and, at amplitudes lower 
than 600V, cause little or no 
damage. 

But at greater ampiitudes, a 
spike can do real damage. And the 
greater the high voltage surge - 
resulting from nearby lightning, for 
example -the greater the risk of 
harm, especially to solid-state 
devices. 

That's why Zenith now intro- 
duces the Spike Suppressor: to 
protect the susceptible TV receiv- 
ers and household appliances 
you sell or service from damaging 
high voltage surges! 

And the Zenith Spike Suppres- 



sor protects not one, but two ways. 

First, the new Zenith Spike 
Suppressor absorbs most line 
voltage spikes so only a safe volt- 
age level reaches the protected 
equipment. 

Second, heavy or prolonged 
voltage surges cause the Zenith 
Spike Suppressor to cut off power 
completely for added protection 
and to signal the need for a 
replacement. 

That's double-duty protection 
against spikes and reason 
enough for you to siock and sell 
the Zenith Spike Suppressor. Your 
bottom line's another. So call your 
Zenith distributor now! 







wilhoul Spike Suppressor 


unsafe 


1 


HX) 


p 

V( 


DLTS 




marginal 1 




300 


with Spike Suppressor ^ 


safe 


III 
v< 

re 
ri 
a 
s 


this graph, the solid curve represents the excess 
>ltao,e or "spike" imposed on an electric system arid, 
presented by the doited line, Ihe protection provided 
□ usehold appliances as Ihe Zenith Spike Suppressor 
bsorbs the excess voltage and prevents it from 
jrging Ihru the system. 



r £NiTH 



The quality goes m before the name goes on.